Welcome to the forum Jade!
Are you talking about growing orchids inside or outside?? I live down in OC. (almost sea level) If growing inside I don't think the elevation would have anything to do with growing successfully. I guess I never really thought about it. There are some orchids, Cymbidiums, that love our dry, hot weather and are beautiful outside. You will need to bring them inside for some of your snowy days but they can be out most of your year up there. Temps down here run between 35 - 100 and they cruise through it.
If you want suggestions on where to buy plants in So Cal, just ask me! San Diego and Santa Barbara are full of orchid farms.