This is why a monopoly is bad.
Red frog seems to be practically the only seller who has factory sealed versions of these games. Heck, I bet that even they have only a handful (1-3) of each title as it is. There is no competition to drive prices down.
I think they have overestimated the market value of those games by ~$100 or so, but they are free to charge what they wish... as a business, their goal is to make money after all, so maybe they'll get lucky. They did take a risk by laying out money to purchase TZD's inventory. Unfortunately for them, the market for obscure USA turbo games is not exactly booming.
It's not personal, guys.