Nice game for 3 tf2 keys.

CS:GO/Killing Floor I guess. But wait for killing floor to go on a daily sale.

Contagion + something else?

Spelunky. You might find it for less since it's just been on sale yesterday.

Borderlands 2 or Trine 1 and 2

Make a thread on SteamTrades and see what they offer you.

Make a thread on steamtrades with a title,

[H] 3 TF2 keys [W] Offer

You could get 2-3 copies of Grid 2 :)

How do u get those tf2 keys? TF2 trading/crafting confuses the fuck out of me.

Portal 2, Magicka and many others

deus ex human revolution?

sleeping dogs?

CSGO?

Outlast?

COuldn't he get anything that is 7.50 or below right now? Go onto tf2outpost and offer 3 keys for a game that is currently on sale/or one that you want. Thats what I would do.

I can give you some for 3 keys, wow

DOTAAAAAAAAAA
and that game Free to play
LOL :D

Killing floor

Sonic and All star Racing Transformed. It will certainly be cheaper with the upcoming humble bundle

I personally love it, it's like SEGA's answer to Mario Kart 64

Well, Castle Crashers? As you told that one yourself... :P

7-8 copies of fortix or Badrats =)

or maybe try chivalary medievil wafare

I could give you 3 Enclave keys. Good trade?

you can get a risk of rain for 2 keys

I recomend >> The Bridge

I'm going to get TDU2 for about 2-3 keys.I think it's an extremely good deal XD

Outlast, Dishonored and Street Fighter IV Arcade Edition are in the range of 3 keys right now and many more.
just go to steamtrades and type tf2 in the search field and look in the threads yourself for good offers on games you actually are interested.

Left 4 dead, Saints row 3, GTA IV, Portal 2, Battlefield bad company 2, terraria, Dead island, payday and dozens of others.