Here are a few places I've purchased bras from:
http://www.bravissimo.com/bravissimo...language=en-GB http://www.inchant.com/s-3-a-f-cup-bras.aspx http://www.biggerbras.com/
I'm a 36DDD and it's difficult finding my size. I also have bought lots of bras from eBay because I love the Panache and Gossard bras. Panache also has really nice swimwear.
Good luck with your shopping :-)