Having dated a fair share of busty women, and being friends with many others, this is a pretty standard price. Several bigger bra shops near me start at around $80, and go up. A UK Gcup friend of mine has paid nearly $140 for a singe bra before, just because ones in her size are not available through regular retail here, and it's not the sort of item you want to buy with out trying on.
I know. It's unfair but unless I become a seamstress, there's not much I can do about it.
By the way, who is that in your avatar,
NewBustylvr? Wow!