Instructions
List your PS3 games on free online classifieds sites. Place your ad under the listings for your community and under the section that best describes what you are selling. This may be "buy and sell," "electronics," and/or "video and computer games." You can post the games you have and the price you want for them.
Put your games up for sale on an auction site. You can sell your games together or one-by-one. Auction sites may or may not have a "buy it now" option. The key to using this kind of site is setting the price low enough to attract attention, but not so low that you end up selling the games for less money than you're willing to accept.
Video game players' forums can also be used to advertise the games you hope to sell. Check the forums for a "for sale" listing and check posts related to the games you would like to sell. Post an ad for your games along with your contact email.
Bring your games to a used video game store. Some stores may offer some money for your games, whereas most will allow you to trade in the games for store credit.