There's three Tasuki cels on ebay right now. Well 
Two of them are ending really soon, so not 100% 
positive all of them are still there. Only one is 
from the TV series though the other two are OVA.

Tasuki cels are *very* hard to find otherwise...
I've been looking for the past two months 
(*really looking hard*), it's the number one item 
on my wishlist really...The ones on ebay aren't 
quite what I'm looking for though. All the nice 
ones I've come across seem to be permanent 'nfs' 
residents of people's galleries. 

(Just yesterday I offered someone 3 of my cels, 
two cg sketches, + cash for her cel of Tasuki. I 
don't think she she's going to take it. Can't say 
that I blame her.)