just to be the devils advocate here, so far all you have is here-say, not real evidence. it is really a strange coincidence that this guy listed the same thing you had stolen and stated he found it, but sadly in the land of the free, that doesnt really PROVE anything. did you register the product or have the serial number or paperwork of any kind? that is goin to be the only way that you can prove without a reasonable doubt that it is yours.
imagine how bad this could turn if you took the (in my opinion) poor advice to go to this guys house or to confront him with some vigilante action only to discover that it isnt yours, or yours turns up somewhere else or the police find it or, or, or. there are far to many variables in this for you to take matters into your own hands. you have done the right thing, you have gotten the police involved, now let them do their job. i guarentee that they would not be happy if they were investigating this guy, were close to nabbing him and then you storm in and start something that ends up switching the roles and this guy can get you arrested or sue you or some other really bad thing. this kind of lameness happens a lot. there are people who use the loopholes in the law to their advantage, dont let that happen to you.
now that you've involved the police, go back to ebay, call your insurance company about replacing it. all the LEGAL routes open to you, and by all means be helpful to the police and call regularly to check on your case, but dont sink to the level of the perp.
just my advice, i know how frustrating these situations can be and i would hate to see it become a double loss for you.
just my 2 cents, if it is the guy then i hope he pays the price for his crookery, if not its better to have a clear conscience.