If you go to an auctioneer for free information, they will not write down a valuation. They will tell you what a piece might fetch at auction, but they will not agree to be held to that. What it would fetch depends on all sorts of variables. If you want a formal written valuation, you have to pay. Usually a percentage of the value.
If the piece can be identified first then the value might be obvious to an expert without taking it anywhere.Try a couple of photos and I might be able to point you in the right direction and narrow down your search parameters