>>36861999probably the same places you'd buy any other old jap shit. mandarake and yahoo japan primarily come to mind.
I got all but Surge and Brock's months ago on ebay for like $20 each (there's also pic related, not sure why they didn't make one for Koga or Giovanni) with everything included except for some random card in Misty's deck being MIA for whatever reason. Still want to get the last two but either they're far more expensive or I'm just having bad luck at the moment.