Well, it used to be Gene Starwind with Caster
($35). However, I recently purchased a set of two 
cels of Urt, the female wizard from episode 23 of 
Outlaw Star. I gave one cel to a friend and kept 
the other. I am still in shock that I got them 
for about $26. I would show the cel, but I am 
having a BG made for it and I don't want to scan 
the cel until the BG arrives. Here is a 
screenshot of the scene itself. Along with the 
cel I sent my friend, this is only the third cel 
of Urt I've ever seen, and possibly the best(the 
webmaster of Animetime has one that is nice, and 
he was selling it for $500 a while back). 
Congrats on your great Transformers find. You'll 
have to share your gallery with us when you get 
it all sorted out.