In the year and a half that I've owned a gaming PC, I've gained up to around 200 games so far. I've only ever paid close to retail price for maybe 2 or 3 games, and everything else, I've gotten for pocket change. A massive chunk of that is games I'll never feel like playing, but I'll get an 8 game bundle for like $3, which is still significantly less than the one or two games I want by themselves.
Overall, I've probably spent around $350 for my entire games collection, a lot of which are AAA titles like Resident Evil, Borderlands, Battlefields, Diablo, Elder Scrolls, Batman Arkham games, Bioshocks, Fallouts, etc...so I always find it adorable when console kiddies go off about how expensive gaming computers are, because I'd be spending upwards of $2000 to replicate my game library on an Xbox with shitty used games, plus a good chunk of my money has gone towards charity, rather than some Gamestop exec.
PC gaming thread