A long time ago, I aquired an error Pokemon TGC card. It is a Base Set Wartortle, and seemingly normal..until you look at the "evolves from Squirtle" area; there's a little picture of another Wartortle there, not a Squirtle :P It's not in mint condition (the previous owner made some minor indentations around his nose, like he wanted to give Wartortle a mustache or something >.>) but it's not bent or anything, just a little beat.
Here's a crappy phone-camera pic:
I want to try and sell this card (either through ebay or here, if I get sales permission), but I have NO idea what to price it at! On ebay, error cards seem to go for some pretty crazy prices. This particular card (the Wartortle) is only on ebay twice last I checked. One, a Portuguese version, went for about $40. The other, and American one, went for $450 o.O Those were both BIN prices though.
I have no experience pricing rare things like this, and was hoping some of you guys might know what it's really worth..or at least closer to it XD
Please don't make offers on this card, I DO NOT HAVE SALES PERMISSION!