Silver is magic (see werewolf and vampire lore) and so it's real value is approximately 1000 times greater than the face value or going market value for the same coin. It can't be evenly traded for money, only for buying goods and reimbursing debts. That's why you can buy a house for only 10 silver coins (as long as you have 2 witnesses and 2 recording secretaries). Honestly, this guy over paid.