Didn't someone complain about being ripped off by limebarb on here a few months ago? I remember hearing a lot of bad stuff about them.
Well anyway, if I purchase a costume online I, like iluvshijimi, go on ebay. In fact, that's the only place I'd look, unless if it's a really obscure cosplay. Be sure to check their rating percentiles as well as comments left by previous customers. I'd also recommend ordering from someone who custom fits the cosplay to your measurements rather than having you order a S, M, L XL. Lastly, be sure to scrutinize the picture that they provide (of their costume detail). Is it really accurate? Is it worth that much money?
Once you've found a reliable maker it's less for you worry about ^^
Good luck~