I haven't used these sites, but almost all of them seem a bit dubious to me. Check out the scrap price of silver - as this is what the 'postal gold' merchants will be using and will offer you only a percentage of the scrap price. Why not take the spoons to an antique dealer, locally, who may offer a free valuation. You would only get the 'scrap' value from the postal services - where, who knows, the spoons may well turn out to be 16th century Rat Tail pattern by a well known silversmith, and be worth a fortune at the antique dealers.