That cel is one of the repro cels made by studio 
pierrot.  There was a small series they made 
awhile back.

If the cel were the real deal, you'd pay a real 
premium for it.  Since its from the first episode 
that jacks the price up, and because its a key 
moment in the series the price goes up again.  I 
doubt you'd see it for sale for less that $800 -
$1000 if it were the real deal.  Cels from the 
first and last episode are highly sought after by 
the die hard KOR collectors.