Ah...ano...please dont encourage the sale of fake products...
Sellers, please remember that the sale of illegal copies of products is against the Swap Meet seller's rules, and may result in your ejection from the event.
http://www.fanime.com/events/swap-meet• The sale or trade of unlicensed, bootleg, or counterfeit goods is not allowed (e.g. SM, Everanime, Aliors, etc)
If you want a good idea of prices, check eBay. I once got about 10 different promo cards for $2, simply because he wanted to get rid of them.
This is both a good and bad idea. Ebay can be a good way to get the general feel of the market, but...like you just said. You got a bunch of promo cards for cheap, right? That's an unusually good deal, and may throw off preception of the market. The best idea is to use several different sources (of which ebay is one) to sort of "triangulate" the average current market price. Try googling "pokemon card price" or "pokemon card price guide" and check out a couple different sites.
Pokemon cards should be marked with indicators for common, uncommon, and rare, and if it's a First Edition printing it should have another mark for that too.
As a general rule of thumb, rare cards sell for more than uncommon, and uncommon sell for more than rare. First Edition prints sell for more than their later counterparts, and "holographic" or "foil" cards fetch more as well.
There are always exceptions, of course. A particularly powerful (or otherwise sought after) uncommon or even common can sell for more than a rare that nobody cares about. Some runs of certain cards have errors, and these error cards can be difficult to find, making them desireable to certain collectors.
It's all about supply and demand. The more people there are that want a card in relation to how many of that card there are to go around determines value. On the other hand, you might get lucky and there could be a local guy with a Gardevoir shrine in his basement and he just needs that ONE LAST CARD to complete his collection here's a hundred bucks PLEASE PLEASE PLEASE LET ME HAVE IT O_O
You never know... =3=.
