I'm a bravissimo girl, can't buy my bras anywhere else. Fuck 28/30FF/G/GG boobs. At least however when clients ask me to buy a new bra and knickers set I can send them to the website, some are sweet and order in to my local shop to take me in to try on the style they like (instant refund if it doesn't fit), but most others back off on the idea I should have every colour of bra once they see the price. I wish I could get cheap bras, but the best I have is £30, the rest are as expensive as my cheapest corset (£50).
Otherwise for suspended belt, I tend to go to ann summers, or order online from lovehoney. For stockings, pretty much anywhere that does them. Although I have found harmony pretty good for colours (for London SPs).