Where can you buy Pokemon cels?

Recently I've learned that Pokemon cels are very hard to come by, so I was wondering where people are buying/have bought from? I really want one of Ash from early on in the series, but so far I have literally seen nothing for sale on any site. (People have Pokemon in their gallery, so I know they're out there! xP)

I've seen them come up on Mandarake and Yahoo Japan from time to time. You don't need a deputy for Mandarake so no extra fees.

there's an ash and pikachu up for auction on mandarake. i dont remember how many days were left for the auction though.

Thanks very much Birdie and Kira! I managed to learn how to browse through Yahoo Japan, but I haven't gotten used to Mandarake. I can't seem to be able to find that Pokemon one with Ash and Pikachu. Maybe it went off by now?

Nope, it's still for sale & at 23,100 yen as of this typing -

http://ekizo.mandarake.co.jp/auc_e/itemInfo.do?itemId=03012754550100003