Found some old pokemon cards worth thousands. What is the best place to sell them? Ebay? Look for gamer/comicon type forums? Or what?
How do you have any idea of their value until you know what they are selling for in the current market, for the exact card and in the exact condition? If you know that, then you also know where to GET that price. If you don't know how much they sell for on eBay, a very wide marketplace open to all, you DON'T know how much they are worth. Going to the gamer forums is going to give you a lot of 'I got this on eBay for X' and 'I got that on Craigslist for Y'. You can let people on the forums know what you have and if you have something truly rare and great, maybe they'll fight one another for it (on the board), but why wouldn't you just put it on eBay and let them all know about it? You don't know how many other collectors out there might want it that don't use forums. But again, if you have to ask where to sell it, you have no IDEA what it's worth.
are they actually worth that much? you need to get your cards graded if you want to sell them for that much. a card can look mint when its not, things like the wax being smudged or minor warping can ruin a card's value. and the most valuable cards are those never opened or those immediately placed in a protective without being touched by your bare hand. if you just found some old cards in your basement, attic, etc then they are likely a bit weather damaged at best.