If it is a hanken cel of that image, the price, 
while perhaps outrageous, does not surprise me.
It's one of the most recognizable images from the 
movie (and Miyazaki cels are priced in a very 
different range than most anime).

On the other hand, I once saw a Laputa cel from 
that sequence in the movie for only $220 (if I 
remember correctly) and it was at Mandarake as 
well.

Now just imagine a hanken for Nausicaa or 
Mononoke O_o (or Totoro or Kiki for that matter).

Wendy