http://www.gog.com/en/page/xmas09
A bunch of older PC games are on sale there for less than $10, and a lot of them less than 5$. Plus, they're made with their own launchers so you don't have to dick around with DOSbox and such. As if that wasn't enough, they come with scanned copies of the manuals, maps, and a bunch of other stuff.
The downside is that when you buy games there, you have to come to I-Mockery and advertise for them.
