Oh, and as a side effect, you may well have
some dealers stoping buying cels from some
anime/character : If their prices are too near
the "guidline price", they won't want to take
the risk to buy them, import them and try to
resell them on internet. Because after adding
all the expenses, they won't be able to take
a reasonable margin without having to sell at
a higher price than what is listed.
(and yes, that's pretty common : most of the less
popular anime or very valuable cels are like
that : you never know if you will be able to
sell them or not when buying them. So it's
always risk to buy them.)

There is also the problem of who will "decided"
about those prices : Only the largest dealers
and collectors can have a good idee of what the
market prices are. IMHO, you would get a guide
of what people would like to pay which will
have nothing to do with the current market
value...

That said... well, good luck...

Cheers,
Yann Stettler