I am wondering when you buy games is it mainly based on Impulse buying ("I just have to have it, and I have to have it NOW!), or do you budget for games and wait until you have the cash before you buy?
I am a little of both, but I mainly try to wait until I know I have the money to cover the cost of the game. That of course is a lot easier when buying from gog than a new $50.00 at the store.
So how do you shop/purchase games?

Budget, not so much as I have little other expenses. Interest in said title is the main factor.
Also: It's weighed against what I'm playing, how much free time I have, and how much of my internet cap it will eat up. (I would like to get TOCA3, but it's 50% of my monthly limit, shared amongst two other people (plus the chances of a corrupt download))
Though I love the lack of a client requirement for GOG, I also like how servicesapps like BitTorrent and Steam handles downloads.

I'm in a somewhat similar situation to Ois. I can afford any game I want, but I always research before buying to be sure it's a game I really want, to make sure it's not full of bugs (or at least that there are/will be patches for it), to be sure I have time to play it, and finally to see what type of DRM (if any) it includes. Certain DRM schemes are instant 'no buy' flags for me and this has, unfortunately, caused me to pass on a number of titles.

it changes from time to time.
right now I'm saving up for a move, so budget.
but later this year I'll be probably more towards impulse.

I get MAYBE 5 games a year because I have this anal thing about not buying games that are generic crap or that simply suck and that seems to be going against the trend of development. With that in mind it's pretty easy to budget in advance for the few things I'm interested in.
GOG stuff on the other hand is pretty much pure impulse, often picking up games I never found originally or replacing ones I have on formats that I can't use anymore. Broken Sword 2 & 3 are good examples, I have 1 & 2 on PS1 which no longer works and I have 3 on xbox which isn't one of the games you can play on the 360,definitely nice to have the PC versions, I HAVE BS1 on PC but I'd also like to own it if you get my drift...
You've got a 30GB limit for a month? Who are you with? it's not telstra surely?!? Don't you get peak & off-peak stuff? I've got 160GB ADSL2+ for $80/month through Netspace and I live in wagga where... well lets just say that the local definition of a job in IT & Telecommunications seems to be selling mobile phones at a shopping centre kiosk... A torrent based distribution option would be nice to have, it'd help take the strain off the GOG servers as well, I know I've got upload bandwidth sitting there unused so I'd be happy to seed them.
Download limits really suck but at least I feel like I'm getting enough to last me a month now. Still paying too much but it's the best value for gig I've found

I am an impulse buyer. If there is money in my bank account, I'll find some way to spend it on games (or game-related products). Case in point; I just ordered 20 Umbrella Corporation patches. I keep telling myself I'll use them in a movie I have planned out in my head, but I doubt it'll go anywhere.
People have download limits? What companies do this? Boy, am I glad I live in Texas so I can take advantage of that fan-dangled new technology known as FiOS.

I'm usually a budget gamer, because when I buy games I usually care about the things said about it (I subscribe to PC Gamer and P:TOM). But if it's a game that looks good on the cove, I'll sometimes go out on a limb and buy it. Like TRUnderworld. Still haven't gotten over that.
BTW, download limits don't exist here in Hong Kong, where broadband penetration is near 100%, and fiber optic Internet is crazy cheap. What you people pay for for FiOS, we get double the speed at half the price. Not gloating or anything (as if), but it's the truth.

For me its a combination of both. I usually just wait and buy them cheaper used after they come out, but a few I have to buy when they come out, like Fallout 3 or Left 4 Dead. Then there's also moments like when GoG put all of their RPG's on sale for 15% off - I went and bought all of them except the Fallout games, which I had already bought off of here. This will probably be my last splurge for a while though (unless GOG puts up the Black Isle D&D RPG's), I'll probably buy the Fallout 3 DLC when it comes out, though. Since I don't have a job anymore and when I -do- get a job I plan on saving up for a nice new PC....

I'm definitely a budget gamer, but ironically all my GOG purchases have been absolute impulse buys.
Download limits are rather common and are becoming more common every day. in fact, Comcast (the second largest US broadband provider) just instituted a 250GB monthly download limit in select markets and will be expanding to all their US markets eventually.
My mother just got FiOS and hates it. The speeds she gets are not even close to consistent; one day they are blazingly fast, the next its like she's back on dial-up. She supposedly has 10Mbit down/2Mbit up and my cable connection at 6Mbit down/1.5Mbit up runs faster and works more reliably. I'm sure FiOS will eventually get better, but for now it is just too new (in the US).

Even worse, It's 12Gig a month. (Shared amongst the three of us in this house, it's 4 gig each D:). And Yes, It's Telstra. No Off peak, and uploads count to the limits D:
(For example: I purchased the Unreal-Pack of steam when it was released. By the time I had UT3, it had been discounted, quite a bit D: This being the reason a client or torrent is useful, as it's easier to delay and have files checked. Still prefer not to have one though.)
I'm 15 minutes or so north of Gawler SA, where, up until recently, there has not been any other options. Looking into switching though, as we are also paying that $80 a month but for such a small amount!
Australian rip-you-off Companies. Especially our largest Telco, "Testra". They've been kicked out of the big future broadband plans though, so it will be interesting to see what happens considering how much of the network they own.
I think you'll start to see download limits (caps) in the US soon. I remember reading Comcast (or one of the big ones) was looking into imposing limits, Starting at 250Gigs, due to all the people (around 1% apparently) downloading stuff via torrents.
Arstechnica has had a few writeups on such plans, but it's been quiet for quite a while.

Yeah I remember hearing about the comcast caps and remember laughing about how hysterical some american posters were getting because they're ONLY going to get a quarter terabyte a month & saying it'd destroy the internet and was somehow a free speech issue (is there a law for internet discussions bringing up free speech thats similar to godwins law for bringing up nazis? If not there damn well should be). What limits WILL destroy is the chances of IPTV bcoming mainstream
Telstra is the single worst ISP in the country (with the exception of crappy resellers who
only onsell telstra crap and add a few bucks for themselves) and I'd not be surprised to find them listed in the top 10 worst on the planet.
Telstra have an entry level plan for $60 a month (if you have your phone service with them as well, if not it's $10 extra) that is adsl2+ speed (they call it 20mbit but thats only applicable if you're next door to the exchange) and give you a whopping download limit of... 600MB. Thats MEG, not GIG. Guess what else is fun? Unlike most semi-civilised ISPs, they don't slow you to 56k speed when you go over the limit, they keep your speed at maximum and charge you for the excess... at a rate of 15c per MB. Again MEG, not GIG.
Say you were on this plan (and had your phone bundled) and wanted to download a 4GB game from GOG, you pay your $15 (roughly how much a us$10 game costs us) and you download it. you're having fun playing it until your next internet bill comes out of your account and you realise that you've actually paid $599.40 for your cheap $15 game... What a bargain, it comes in at UNDER $600!! They've started to introduce a few plans that slow you rather than overcharge but they're still a major ripoff for the price.
This is the reason that I tend to scold people when they tell me they're using telstra.
Ois, have a look at netspace.

MY ... PRECIOUSSS ... NEED ... MORE!!
When I have money (and I have lots lately), I'm an impulse buyer! But I usually don't regret buying pretty much anything, I do some research... Not much though...

I'd consider myself a budget gamer, but things below the 10$ mark tend not to register as expenditures, i.e. there are some impulse buys in that category. Otherwise, there's nothing I'd need to have so much as to be willing to fork out 50$ for it. If it's a great game and the developers deserve the cash, then sure, it happens. (Once a year, and around Christmas, actually.) I guess I could always pirate them if I was dying to play them - but If I'm willing to put significant time into a game, I'm willing to put cash into it as well. So it's quite rare that it actually happens. (With newer games, anyway, abandonware is a different matter.)
Now that I'm checking things, I think I've actually spent about 250$ on games last year, half of which is from the 10$-or-less category. Ouch. They really should damn well register as expenditures, it seems.

Internode are a bit more expensive (and I think you have to pay quarterly rather than monthly though that may have changed) but they're definitely worth it if you download a lot of stuff. They run what is basically the main australian download mirror for almost all gaming & IT sites on the net so if you need a patch, demo, video or other file, you can download straight from the ISP and not have it come out of your download limits. A mate of mine used to get about 50-60GB of game related stuff a month on a 30GB plan and he always had heaps of data leftoer at the end of the month.
url=http://www.whirlpool.net.au/http://www.whirlpool.net.au/]http://www.whirlpool.net.au/[/url[/url]] the broadband choice thing in the top right is the most comprehensive comparative list of ISPs I've seen