Bebop Man wrote:BioShock - $20
Dead Space - $20
Resident Evil 5 - $20 (Gold Edition, $30)
Red Dead Redemption - $20 (Game of the Year Edition, $30)
Portal 2 - $25
Batman: Arkham Asylum (Game of the Year Edition) - $25
Journey / Flow / Flower - $40
God of War Saga (GOW 1, 2, 3, Chains and Ghost) - $50
Bioshock: Great game and considered a classic by many. $20 is pretty high considering it came out so long ago. But that's likely the best price you'll find it on without a sale.
Dead Space: The original Dead Space was pretty good. But, if I were you, I'd just get Dead Space 2 or look for a combo pack (you should be able to find one for maybe $10 more. But I feel Dead Space 2 is the superior game in nearly every way, and the story from DS1 is explained well enough in it.
RE5: A lot of people disliked RE5. I thought it was pretty good. The forced co-op bothered me quite a bit, but I had fun with it. It's not nearly as good as RE4 (which you should find and get if you've yet to play it). But it's worth picking up in my opinion. Not sure on gold though. I'd say it's not necessary, but it wouldn't hurt.
Red Dead Redemption: It's a very good sandbox game with a lot of things to do. I'd say it's worth picking up. I'd say gold is worth it because I've heard Zombie Nightmare is very good.
Portal 2: Not as good as Portal 1, but still very good.
Batman: Arkham Asylum: The newer Batman games are both really solid. I'd recommend looking for a combo pack if they have it with both Asylum and City.
God Of War: I don't like God of War that much. But if you like hack-n-slash games, you could do far worse.
Between all of those, you should have months of gameplay. Some more good PS3 games I could recommend would be:
Infamous 1+2
3D Dot Game Heroes
And there's likely more I can't think of.