I have purchased from them, online and the Orange County(CA) store. I did buy that exact lens from the San Francisco store during a trip up there.
I would call ahead to make sure they have the lens or order it for you, they do not seem to keep a very large inventory.
I have noticed a few of the sales reps in the OC store try to upsell a lot, so beware for the "this is a third party lens, and we get lots of returns on it" line... They just might try to upsell you to the Canon equivalent. That might just be this store, just dont believe every word that comes out of a sales rep.