Looking for Magic:the Gathering players in Orange County, CA?

Well, I would go to Wizard's web site and look for other stores close to you. As to the store you go to, if they do not allow trading (as opposed to selling cards which they should not allow you to do) I would report that to Wizards. The whole idea of MtG is to be a trading card game and i do not believe they can legally forbid you to do so.