The mirror is available from Pottery Barn for $449, but I think it's been out for a while now and should be going on sale soon. Be sure to keep a close eye on it though, PB sale items seem to really fly off the shelves.
P.S. I notice some (much smaller, but much cheaper) substitutes on eBay. But if it's in your budget, I'd hold out for the bigger, nicer version at Pottery Barn.