Fixed, although not sure what you mean by sold under medal value.
Basically, when you're selling items at the pawn shop, it just refers to the coin all the time, and you get nothing from it. For example when I try to select 'Fang of the Magical Beast' which sells for 43g, it just says 'You have 0 of the Old Madonea Coin, so...' and then offers me 0g for it, and if you do select sell after that, you lose the item so yeah... probably something messed up with the variables. Also in the Priege, when you leave the pawn shop, the text there is bugged, the shopkeeper says "l49- pawn shop,S{ N_0} 'Thank you for the purchase' so yeah, might want to get that looked at too