actually, there are rumors that stealing is one 
of the reasons Disney has now shut down their 
archive.

people would steal whole scenes of vintage disney 
animation and then sell them to animation art 
galleries for a pretty penny.

as to prices,... here's one example.  an animator 
who worked under Glen Keane on Ariel (The Little 
Mermaid) got an original production (key cel) of 
ariel from a glen keane scene for a few hundred 
dollars (about 600$ I think?) or maybe it was 
$300. point is, that cels from this film were at 
that time (and still today) more in the $1,000 to 
$3,000 range.