As to buying a cel, check with Ed Noonchester
http://www.ednoonchester-artwork.com/cell_index.ht
m
Ed did have a Kashue for sale a while back but 
image was kinda dark

Galleries that have Kashue cel that could think of 
immediately, know there is another OAV cel w Parn 
& Kashue together but cann't remember which 
gallery

2 OAV cels here
http://www.mse.eng.ohio-state.edu/~ms_bryan/Lodoss
.html
1 TV cel here
http://www.geocities.com/Tokyo/Pagoda/2815/lodoss.
html