Well, the one thing you prepare yourself for with the online one - its not going to look exactly like the photos unless you go to heiphy whose images are the dresses they make, not dresses they impersonate.

I was going to get their strapless corset dress - utterly gorgeous - but ended up buying a replica from another seller. Not much like the photo but still beautiful and it was delustered satin so I stumbled onto a decent seller at least. Problem is trying to pick one who is. Definitely check the feedback.