For games...
TF2: $20
*Half Life series: $50
*CS:S/Gmod: $25
L4D: $40
GTAIV: $50
COD4: $40, I think.
That's $225 for some of the best games we've ever had, if you feel like spending that much. Spend the rest on songs and crap if you really feel the need to spend it all.
But that's just games, I'd spend $250 on something else.