Why are bras - especially for the larger chested - so flaming expensive?

[CambridgeBlue]

I really need a new black bra as the wire has poked right through mine but I couldn't find anything in our local town this morning for under £20 in my size (34FF) and it's a similar story online. I resent paying so much for underwear, it's such a dull thing to spend money on!

I'm a 34G and try and buy my bras in the sale, great discounts especially places like Debenhams. You really can't skimp on good support if you're a curvy girl!