Mailing would probably cost me more than I make from the cards since I live in Europe.
eBay has websites for specific countries only.
And, depending on the variety, and age, and quality and rarity of any cards you have, you could have cards worth a decent amount.
Collectors will probably pay for rare cards, more than enough is necesarry to cover your Post&Packaging (Or, add this onto the price, which you can do on eBay), and the percentage that eBay takes, plus any taxes.
Or, find someone you know who is interested in them, or a shop that deals in those sorts of games/toys/items.