Hey there!

Well... I just scored a great cel of Kouryuu with 
eyes wide open and it's sketch for $300.00 at 
Asylum Anime. 

I've seen cels of him in his Chibi form go for 
$200.-$400. depending on the content of the 
image. Close up... Eye's open... Cel condition... 
Has sketch... etc...

Hope that helps!

Sincerely, Harry