Yep $10 is about the going rate on those, in fact I have all four of those and I paid less on ebay. But like Keir suggested you might try and make a deal on all of them together. If it were me, I'd offer $20 for the set of four, $5 each, and then if they counter with $30, I'd offer $25 as a final offer. It all just depends on what you want them for. If you are gonna start collecting, then even at the $40, it's not so high you shouldn't buy. But you may could find on ebay for less if you are patient. So you could buy at their price, but I'd try and work a deal, and the lower the better when dealing with junk/antique shops.