Here are some links to sites that have awesome gear for sale online:
http://www.heavyred.com/index.htm - Gothic, women and men's clothing, a beautiful site.
http://www.asylum7.net/ - Some colourful stuff, more cyber Goth.
http://www.art-of-dark.de/de/index.shtml - A site in German but easy to navigate, the demoninations are in Deutch marks so will have to be converted!
http://www.house-of-harlot.com/ - Fetish gear.
http://store.yahoo.com/akaara/ - Stunning clothing, a great variety and also Fetish gear... stunning corsets too!
http://www.meschantes.com/index.html - More corsetry!
http://www.jeannienitro.com/index.htm - Some nice corset dresses, but not really that many that I personally like...
http://www.corsetmaker.com/ - A rather striking site, and as the url suggests.... Corsetry, beautiful and vintage looking!
http://www.geocities.com/FashionAvenue/Mall/3538/ - House of Ill Repute, I like the name, a couple of alright dresses and things.
http://www.realcorsets.com/ - Corsets!
http://www.hedoniagallery.com/ - Very avant garde site, I like....
http://www.houseofanoria.com/ - Medieval and Renaissance style dresses.
http://www.gownofthorns.com.au/ - A bit of everything.
http://www.gothicauctions.com/ - The biggest auction site dealing exclusively with things of a Goth or fetish nature.
http://www.gothauctions.com/auction/XcAuctionPro.asp - Not to be confused with Gothic Auctions this is an entirely new site. Gothic themed and designed with free selling and buying including free picture uploads and a message board.
http://www.gothique.biz/ - Nice site though I've not really searched it that much, I don't really like the colourful corsets though, perhaps some people would.
http://www.gargoylesclothing.com/ - The name says it all, a shop based in New Orleans.
http://www.girdlebound.com/ - Another vintage style site.