Oh, and just one comment : if someone was going to 
make a fake, he wouldn't go around doing a whole 
sequence : far easier to make several copies of 
the same cel. (not counting that some of those 
cels definitively don't have the same value as 
others...)

One more thing : I can't speak for all those cels 
but some where purchased, without any doubt, when 
the movie was first shown in theater and when 
those cels were sold to people going to watch it.
I don't much believe in people taking pictures 
during the show and then painting whole bunch of 
cels during the few days cels where available in 
theaters...

Cheers,
Yann Stettler