Decent ones only come around once in a blue 
moon.  I love the movie, and all of Umesu 
Yasuomi's other works too, and have managed to 
build a small but fairly decent gallery of Kite 
cels for myself.  Click on the link above to 
check it out.  And please email me with offers if 
any of them catch your eye.

But cels are quite hard to come by, even for the 
dealers.  I have had the most luck finding Kite 
cels at Conventions.  Most dealers I find have 
one or two cels from Kite, and for them, it's not 
worth it to take the time to scan and post just a 
few online.  They'll just keep them in their 
books to sell at Cons.

Hope any of this information helps!