First of all thank you for your time.

I want to buy some DLCs for those games.
I don't care about weapons, armor and appearence, so I think, but feel free to correct me, that these are important:
Mass Effect 2 (I have it both on Steam and Origin) :
Lair of the Shadow Broker
Overlord
Arrival ??
Katsumi ??

Mass Effect 3 (Origin)
Omega
Citadel
From Ashes ??
Leviathan ??

All of them require a lot of Bioware points, which translates in a lot of money (I got Mass Effect 2&3 for 6-7$ each).
Where should I buy them from? Do they ever get a discount?
Thanks a lot!

You should buy them from Bioware.
About discount... I don't think they ever get discount.

Btw Arrival is probably the best DLC for ME2 IMO

Those are all of the story-based DLC, yes. Kasumi and From Ashes mostly add new NPCs to your team, with an associated storyline, while the rest are a series of missions.

ME 3 DLC can only be bought from Origin AFAIK, while you can buy the ME 2 ones from Origin or Bioware. I don't recall them ever being discounted, but sometimes there is a slight discount on buying Bioware points.

You must buy them via Origin or Bioware Social Network... I'm waiting for a discount as well (for ME3 dlcs) but the chances of this are... slim

I have all story DLC of Mass Effect 2 and they are pretty good. The greatest defect is that they lasts only a couple of hours each.

Thank you guys!
Unfortunately you are confirming my fear that these things don't get discounts. There is no hurry, I can buy them next year, but I wont pay that much, that's for sure.
I still hope someone will say something positive :).

Mass Effect 2 DLC prices:
Lair of the Shadow Broker 800 Bioware Points = 8 $
Overlord 560 Bioware Points = 5,6 $
Arrival 560 Bioware Points = 5,6 $
Katsumi 560 Bioware Points = 5,6 $
Total: 24,8 $

Mass Effect 3 DLC prices:
Omega 1200 Bioware Points = 12 $
Citadel 1200 Bioware Points = 12 $
From Ashes 800 Bioware Points = 8 $
Leviathan 800 Bioware Points = 8 $
Total: 40 $

64,8 $ for all the DLC. These guys are crazy :).

..and that's why you don't buy anything from EA. That's what I do :D

Most of them are worth it if you really love the games. If you really loved the games though you would own them by now, so... none of them are essential really. If you want to just get a couple I would say Lair of the Shadowbroker and From Ashes.

Not to mention you'll have to buy Bioware points instead of paying with real currency, so you'll end up paying $64.80. Personally, I won't be buying until they release a Game of the Year/Decade/Century/whatever version with all the DLC included.

That's not ALL the DLC - esp for ME2 - take it from me... I bought ALL the DLC for 2 and 3...
but yeah... expensive... and will NEVER go on sale!

they already did that. And this is what you get

On PC, Mass Effect will include Bring Down the Sky and Pinnacle Station on disk. For Mass Effect 2, Cerberus Network will be included which features Zaeed – The Price of Revenge, The Firewalker Pack, Cerberus Assault Gear, Arc Projector heavy weapon, and Normandy Crash site mission. For Mass Effect 3, Online Pass will be included granting players access to co-op multiplayer.

sauce:
http://masseffect.bioware.com/about/trilogy/

So, no DLC, you need to catch them all :D

Only Bring is free and if you have on steam you have open a ticket so you can have the dlc cd key.
For Pinnacle: http://store2.origin.com/store/eaemea/pt_PT/pd/productID.152041300/sac.true

As for ME 2 and 3 dlc :

Lair of the Shadow Broker
I Liked the story(Liara got a lead against Shadow Broker), you have car chase and 2 unique bosses battles.
Overlord
The atmosfere,the boss battle and the final choice.
Arrival
Only if you want to understand the begin of ME3.For me the only good thing about this dlc was the gaunlet.
Katsumi
The dlc is short, have a boss battle, an op SMG and a new squadmate which teleports behind an enemy which is good against heavy mechs because turn their backs to you.Sort of meh.

Mass Effect 3 (Origin)
Omega
For me this was prime example of a dlc i wouldnt buy(but i did) video glitches,dull, 2 new enemies( 1 of them was a waste because it have the most unique ability and bioware could done something great with it instead its a generic enemy),a stupid(personally the worst even beat the ME 2 last boss) "boss" battle which again Bioware again wasted opportunity (due Aria and Kai Leng history could been a fight between them 2).The only good thing is female Turian but she isnt with you all the time.
Citadel
Yes the boss battle alone worth the money(try Sentinel past hardcore(forgot the name) mode.Its a fan service dlc regardless it adds the amusing banter with all and between MEs squadmates, most enemies are reskin cereberus(though only 1 comes mind with a new thing) and Wrex as squadmate and almost forgot an arena pretty much like Pinnacle Station but you can pick up squadmates,enemies and " buffs and debuffs" to make harder/easier(there are mission related to arena which requires specific combinations) and new weapons.
The down side are the dlc appears only after attack on citadel by cerebus which means Thane and Mordin are dead(though they left a memento) and the most important thing:in order for any previous squadmate to appear and Tali , you have to do their sidequest/Quarian/Geth and its best(personally) do this dlc before assaulting cerebus station because by that time you unlocked Miranda path.
From Ashes
Pretty much like Kasumi dlc, new weapon, new squadmate and some funny banter.MEH.
Leviathan
For me this is a mix MEH and dont care.Beats Omega in dullness.

Myself got all dlc(not the weapon and costume)eventually just for all the experience.

Nothing to add. Couldn't agree more.

PS: I have all DLCs as well, except for Omega.

Thanks for sharing your opinion!
I do know that those are not all the DLC. I picked only the ones I think were interesting, but it seems I have to give up on most of them.
I love the games but for me that is a large sum of cash, so if EA won't offer a discount (at least 50%) they won't see my money.
Thanks again guys!