My favourite place is http://www.misfitz.org. Not least because their only retail outlet is in the town where I live, but also because their clothes are really nice. They do some fab corsets, off the rack *or* made to measure, & they are excellent quality too. Their email isn't working at the moment, but I believe their phone no is on the website, if you want a mail order catalogue.

Another place I *haven't* tried, but have heard is very good, is http://www.candscorsets.com