I think I would be calling the pawn shop too and asking them to call the owner. Offering them some money for their trouble and reward if they help get it back should do the trick. Going through that shop is really your best bet. I wouldn't outright tell anyone how much you want to put on top of the fair market price. I would explain the sentimental value and offer a price of 150% of the fair value. Good luck, I hope you come up with it!