I don't think you'll get much "luxury" design from most online shopping stores, even though you're building one. Each link above offered a "luxury" product but their website was plain -- albeit perhaps very usable, but not what you're asking for, right?
Maybe go checkout sites that have to "show" luxury but aren't selling luxury products on a piecemeal basis. Casinos, resorts, stuff like that. Get a feel for the luxury "wrapper" of those website and throw products into it, or something. *shrug*... Fuck, I dunno.
Casinos:
http://www.venetian.com/
http://www.trumpcasinos.com/ -- same as above, or vice versus.
Or, if you're really bored, go through some design websites.
http://deviantart.com has an interface & design section (go through top rated) for kicks.