I agree with Ironlord and Wayward. Silverplate just does not hold its price at all. If that was on a car boot table over here it might be priced 50p and still not get a buyer. Nice Victorian pieces, Sheffield Plate, and real 'statement' pieces can still fetch fairly good prices, but a fraction of what they did 20 years ago.
You seem to be really enthusiastic about your purchases, which is great, if you like it, buy it. And the value of that piece is what someone is prepared to pay for it at that time, so if you pay $10, then that's its value at that time. But that does not mean the value will still be the same when you want to sell it on ... it could go down to $1 or up to $10.
If we could predict prices, we'd all be rich!