metal gear solid 4 is new from gamestop for 20 bucks lols
http://www.gamestop.com/Catalog/Prod...product_id=105

assassins creed is 20 bucks preowned
http://www.gamestop.com/Catalog/Prod...oduct_id=60750

uncharted is 25 preowned
http://www.gamestop.com/Catalog/Prod...oduct_id=64961

and

marvel ultimate alliance for xbox360 is 5 bucks..... and marvel ultimate alliance 2 for ps3 is 25 bucks

these should give u a more accurate gauge with which to mark your prices.

your prices are so expense!
but umm good luck with your sales.