I'm planning on picking up:
•RollerCoaster Tycoon Deluxe (includes RCT 1 and both expansions) - $2.59
•RollerCoaster Tycoon 2: Triple Thrill (includes RCT 2 and both expansions) - $4.39
•Banished - $5.49
•Unreal Tournament 3 Black - $5.49
I actually own RCT 1 and 2, but for the last 5 years I haven't been able to find my RCT 1 discs and my RCT 2 game disc (I have both expansions but no idea where the game disc is). So I figure hey, if they're this cheap, I might as well re-buy them. They're fantastic games. I might even buy RollerCoaster Tycoon Classic Collection which includes 1, 2, and 3 and all expansions, just so it's easier to one-click install them down the road ($12.59).
I currently have RCT 3 and both expansions installed from disc, but not updated. I remember if you ran the updates for the games and updated all the way, there was a really annoying bug after you patched that caused clicking on any info item for a structure to lock up the game for ~10 seconds. So I'm hesitant to run the game from Steam just in case they never patched it past that.