I think that GengaEDouga is more expensive than 
cel to be wrong, too.

But, as Ryouko says, the thing which a famous 
person drew will be of value.
The charm of DougaEGenga is thought to be the 
line drawing of the own handwriting.
There are many things which don't have Douga in 
recent cel, and I am sad.

Because it turns with CG, cel is disappearing 
with Japanese anime.

Therefore, Douga and Genga are merchandised.