I did a search for anime cels, and checked out 
the anime category in collectibles on Ebay Japan, 
and didn't see any cels.  (I can read katakana 
and hiragana, so I'm reasonably sure I was 
looking in the right place.) There were only 
about 30 items total in the anime category.  So 
either we're both doing something wrong, or Ebay 
Japan is just not the place for hip young 
Japanese folk to sell their anime merchandize.  :)

Reene