If you're looking for the perfect prom dress and are imagining the photos that you'll have for a lifetime, you might want to consider how that could end up looking if you buy a cheap, knockoff dress online.

It is easy to get lured to sites, typically based in China, that appear to be offering name-brand dresses at deep discounts. These sites tend to actually fulfill orders -- they're not really big on returns -- and what you end up with is anyone's guess. But expect a cheaply made imitation of the real thing.

The American Bridal and Prom Industry Association has already identified more than 450 counterfeit websites that have sold more than a half-million counterfeit gowns. Indeed, knockoffs of all sorts are a continuing challenge for online shoppers.

But your prom dress? Do you really want to take that chance?

"It's hard to visit any online venue without running across sites that are hawking fakes. Worse still, it's getting harder and harder for consumers to discern the real McCoy from the fakes due to clever marketing, slick sites and plausible discounts from counterfeiters taking advantage of digital channels," said Fred Felman, CMO of the brand protection firm MarkMonitor.

What consumers stand to lose can also be far greater than just the experience of receiving a junky dress.