Cels Forum

Rarity and beauty play a large role in the value of 
backgrounds.  A matching background for a Miyazaki cel
is going to add a lot of value to the cel because
the backgrounds themselves are prized and collected for
their beauty.  In fact, there are Japanese collectors 
who collect _only_ the backgrounds from Miyazaki titles, 
not the cels themselves.

And if you consider a two or three-fold increase in price
bad, consider the situation with some Disney titles.
A Disney cel that might fetch $3000 could very well fetch
$30,000 or much more with a matching handpainted
background!  You're talking about ten-fold or twenty-fold
increases in price!