I've been in school so long that I've learned how to be very frugal with game purchases.
* If it's not on the PC, get it through GameFly [http://www.gamefly.com] or like service. $25/mo for all the games you can play (2 games out at a time that are mailed back and forth) is affordable enough. Even if you decide you want to own games, you can usually get them half-off (give or take a quarter) if you rent them through GameTap and opt to keep them.
* If it's a PC game that's a few years old, it might be on GameTap [http://www.gametap.com], another good subscription service. Though I think they're losing it lately - they lost lots of good old licenses and don't get many new ones. (If it's really old, sufficient Google-Fu might locate it as Abandonware, but don't fool yourself - it's just another kind of piracy that's less likely to be enforced.)
* If it's a newer PC game, don't buy it right away, wait for the price to drop. It's really not worth spending $50-$60 on something now you can play for $20 a year (or sometimes even months) later.
* Then, of course, there's the new price for PC games: free. I'm not talking about piracy, but rather the ton of Free2Play MMORPGs and web or indie games [http://jayisgames.com/] you can find these days. Like World of Warcraft? Give Runes of Magic [http://us.runesofmagic.com/us/index.html] a try some time - it's a some-ways-better-some-ways-worse alternative with a much more managable price tag. Even Dungeons and Dragons Online [http://www.ddo.com/] is going free to play. Basically, there's so much competition out there that there's a ton of developers that will give you something for free just to get your attention.
These are interesting times we live in.