There are plenty of Blue Gender cels out there. 
You should have a look at the 'few' cels Yann has 
for sale and in his collection hehe.
Animaxis has had some very nice backgrounded ones 
for sale but they're not cheap (9000 - 12000 yen 
for the good ones)

Anyway, this is my one and only Blue Gender cel 
(so far). Thanks to Yann.