Q) WHY do you like, or do NOT like, purchasing/selling cels 
   on EBay or another auction site? 

Hmm.. Well, as far as buying cels there.. I hate the prices
that they generally go for there. I have purchased a few
cels there - spent way too much on a couple (but I love them
anyway =P), and got some incredible bargains too. Just got a
bargain today as a matter of fact! ^_^; I hate snipers, but
I've turned into one myself... ::shrugs::  Can't beat them,
might as well join them. I generally don't put a "real" bid
in until the end of the auction so someone doesn't put 18 
teeny bids to push me to the max. -_-;

I also HATE shill bidders with a passion.

Selling on ebay - well, I don't sell many of my personal cels
there, and when I do I generally email other collectors first
to see if they might be interested, and then put them for
sale on my site first. If they don't sell, I will put them on
ebay. Ebay does get a lot more hits generally then a personal
gallery.. so more exposure. 

Just my thoughts.
Sheri