This past year I bought
Fallout GOTY
MW2
dragon Age
Mass Effect 2
Uncharted 2
Demon's Souls
Fifa 10
jak II
half Life
Deus ex
red Dead redemption
6 cost £30-£40= roughly £200
1 cost £20-£30= £225
1 cost £10-£20= £235
3 cost >£5 = £250
But i sold MW2 for a profit, Fallout almost what I got it for, the same for FIFA 10, Mass effect 2 and various games i bought last year.
I probably ended up spending around £100 all told
edit: also Alan wake- bought for £40, sold for £30
and Heavy rain- bought for £40, sold for £35