Goto ebay.com and search for the name of the game you want, set it to find only Buy it Now auctions, and put lowest priced first.
You can get brand new, unopened Gamecube games for as low as $25 doing this, and shipping is usually no more than 5 bucks.
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=1389824557 - Spiderman, 30 bucks, free shipping.
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=1387968776 -Smash Bros. Melee, not brand new but he says it's in fine condition and he has excellent feedback.
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=1389062897 -Animal Crossing, 45 bucks to buy right now and only 20 if you wanna try and bid for it.
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=1389712487 -Super Monkey Ball, Brand new, buy it now for 30 bucks.
I'm just sayin if your looking for a game you should try on ebay first