I need a shirt.

I've been asked to perform two wedding ceremonies this year. I love doing weddings, so I'm really excited about them. However, one of the couples has asked that I wear a collared shirt (and we're not talking polo here). So I've been looking for an ecclesiastical supply store in Los Angeles that would have said shirt, but so far I've come up with nothing. Any suggestions?

Edit: Thanks to jeanniemac I have the shirts I needed. Thanks!