FantasicaTrading-Unofficial.com is a site that can give you a good idea for how much a card is worth. It's currently actively maintained and the values are fairly accurate. As with all prices in Fantasica, this is a great guide but don't think that any of the numbers on the site are 100% accurate. It's only meant as a guide to get a general idea for what a card is worth.
The Fantasica Trade Wall is a simple page that functions much like the Recent Card Report in-game. You can browse and post ads with what you're selling or looking to buy without having to constantly refresh the RCR.
