Keeping my list for games for 2 bucks and under to be considered actually cheap. ;)
First thing that always comes to my mind:
FlatOut 2. One of the best arcade racers ever made.
Also,
Tomb Raider: Anniversary. Now this is how you do a remake. The original TR was good, but this vastly improves on it. Still my favorite of the franchise. :)
Also also,
Zombie Night Terror. Lemmings: Zombie Edition. Enough said. ;)
Also also also,
HuniePop. Dumb, dumber, and not exactly family friendly (especially with the adult patch applied via a dummy file). Even so, it's a very well made and fun puzzle game. Still better than the sequel.
Also also also also, two of the best adventure point-and-clicks from Daedalic:
Anna's Quest - Dark fairy tale world. Does feature a child protagonist, but it's definitely not for kids.
The Night of the Rabbit - Also an imaginative fairy tale world of a different kind.
Also x 5, at above 2 bucks by a few cents
Outlaws - Lucas Arts's Spaghetti Western FPS
Star Wars: Dark Forces - Doom: Star Wars Edition
Star Wars: Galactic Battlegrounds - Best Age of Empires ;)
Also x 6,
Race the Sun. One of the better examples of small procedural games done right. Literally chasing your own high score. ;)
Also x 7,
Roller Coaster Tycoon 2. A true classic, best played via OpenRCT 2 these days.
Best bought with
the original Roller Coaster Tycoon, making both an average of two bucks each. ;)
Also x 8,
Unreal Tournament. Featuring some of the best bots in FPS history, and in-game online matchmaking is still supported to this day. 2004 may be technically superior in certain aspect, but its bots are completely incapable of doing well outside of classic run-and-gun (worst drivers ever!). Even that aside, I usually still find this more fun to play nowadays.
Also x 9, two of the best and only (?) good castle RTSeses (just don't bother with the extreme versions because they're fubar):
Stronghold HD - Great for its campaign.
Stronghold Crusader - Better for its skirmish and multiplayer play.