This cel was debated quite a bit on beta.  Here is
the link to the topic:

http://www.anime-beta.com/phpbb/viewtopic.php?t=4615&sid=ae0e81b270cb23bb454fbcadc1199feb

Personally, I think it is a fancel.  There is too
many things about the cel and the seller that are
fishy.  

1.  The cel looks like it is of low quality, the
proportions and color are off.

2.  The seller goes out of his way to try to prove
that this is an actual production cel.

3.  The seller provides false information about
protecting yourself from fraud.

4.  The seller states that there is a matching
background but they didn't show it and refuse to
sell it unless in person.

Please go to the link above and decide for yourself.

Take care,
nesuferit