got 512 ram kit from a friend for free

Got a nice Nokia phone for free along with a SIM card.
Another bargain was getting the first 2 fallouts for like $9.99 at Walmart a while back. They were in one of those dual jewel cases.

You have to remember that haggling uses your charisma stat.
And places, from where those games are bought, are many

Two words:
Flea market

That's a rough deal. It reminds me of a friend who when and bought the Magic expansion to the -really- old version of Warhammer. Literally the next day they pulled it from the shelves and replaced it with the -then- newly updated version which switched the cards to dice rolls.
Its kinda sad, I mean we were regulars at the Games Workshop and he wasn't even told by the manager (who I later found out knew about the rule change months before the event) not to buy it. It actually made him quit the hobby as he'd spent £30 on an expansion which became useless the next day. I think he felt disenfranchised and sapped for money, with no care paid towards his 'loyalty' (we were just school kids). I soon bailed after that, when I came to realise what they did, and after I mentioned it, found it funny. That's sick really, we were only 13 and you can imagine what £30 was to us.

I found Gabriel Knight 1-3 for 2 bucks at Half-Price Books. Along with that is Gothic 3 Gold (Gothic 3 + Expansion) for 7 bucks, and a big boxed copy of Secret of Monkey Island for 10 bucks. I almost got Phantasmagoria 1 + 2 while I was there, but when I cracked open the cases both copies were missing CD 1 :-(

Strategy First Xtreme 6 pack. Aside from the rather awful name, it had Kingpin, Sacrifice, Evolva, MDK 2, Giants: Citizen Kabuto , Fallout 2 for a total of 12USD. Purchased through Auran of all places. This was before GOG was even a press release on the internet, else I might of waited.
There were a bunch of purchases of old console carts off e-bay, that I manages to get cheap and avoid snipers.
Aside from that, I knocked off $100AU off a 640GB external HDD since the store had mislabelled the shelf incorrect.

Pretty good deal was Star Wars - best of PC - for 10 pounds it had KOTOR, Jedi Outcast, Empire at War, Battlefront, Republic Commando and SWG.
Other good deals - Orange Box for 10 pounds, everything on gog..

I second Morrowind GotY PC. I still play it. I must've logged 2000+ hours. It's outlasted 2 girlfriends. Neverwinter Nights Diamond was another one like that for me.
From a collector's point of view, probably the Shin Megami Tensei Games for the PS2 (and the Persona ps1 games and other related games for the DC). I have all of them. I didn't pay more than $29.99 for any of them (most of them sell for $150+). I'm considering selling them soon as a lot on ebay for a down payment on a condo. I don't really have the time to play them anymore.
For the PC, the Blair Witch experience (I paid $6) was another great deal. I love the Nocturne style survival horror games. Plus you got the two movies, too. Oh, I paid $5 for the Planescape/Soulbringer Jewel Case. Soulbringer is meh, but well Planescape is Planescape.

Just got Thief: Deadly Shadows for £2.00 which isn't too bad!
I love second hand games shops.

I ended up with the same set for the same price. I don't remember ever actually trying Soulbringer, but Planescape for $5 was an epic steal.
I picked up Age of Empires 2 and the Conquerers expansion the same way.

Okami for $2.50 used.

Medieval 2 Total War Gold Edition for $10!!!!!

I got Desperados for $5, and it works perfectly (so far, still on level 2) on my Vista.