It would still have to have an FDA APPROVAL. As someone who has taken over 50 class 3 medical devices through the FDA, I can assure you that Gary has this right. If a 510k approval were to be granted it could happen really fast, (I just helped a company that has a new discovery device get one.) The pre existing device had to exist in the US marketplace before 1972. It took us 4 months to get through. Anything more than a 510k could take years and never get approved after all that time in process. Much of a devices class designation has to do with how much risk it imposes on the person for which it use is intended, and the claims that you wish to make about it. For instance both the Vizilite and the Velscope are 510k approved devices. Do they find cancer? Yes. Can they make that claim? No. They have issues with specificity and therefore their claims are that they are general discovery devices and not diagnostic devices. If they step over the line in the marketing etc. they can have the approval revoked. As the previous owner of a class 3 medical device company, I can tell you that FDA protocols, GMP's and the like are one of the major expenses of operation of the company. I manufactured implants, and the paper trail from the purchase of the raw titanium to the inspection of the final product was monumental.

All that said, if someone was in process of FDA approval and they let you try one out, sold you one, etc. outside of their apaproval process, it would be a cold day in hell when the FDA every approved it if they found out.