Give them to me (or at least all of your bugs, pyros and dinosaurs)! = D But ebay или any other auction website is a good option. If Ты have a swap meet или something locally, Ты can also sell them there. или Ты could donate them to Goodwill или any other charity organization.
Since they ARE collector's cards, though, I'd keep and display them. Use them. Maybe start a trading service.