My boobs are bigger than yours still so yes, I know the pain that is expensive bras.
I'm not sure if I'll get shouted at, but a fantastic bra site for big boobs is
www.bravissimo.com!! They are fantastic to order from, there are a few shops - they do bras, swimwear, sports stuff.... get a cateloge.
When they do sales it's like Christmas has come early! =)
Chloe xx