I agree that people should make a profit. When is 
enough though? A 30% return? A 1000% profit? What 
happens then? What if it's not rare, and there's 
a cheaper cel from the same sequence somewhere 
else? Do you feel sorry for the bidders? Or do 
you laugh about their ignorance? 
(Most dealers though, do put up some fantastic 
cels for auction, so this isn't an attack on 
them).  
Honestly, you can screw people for a while, but 
they eventually get the point and drop their 
collections faster than you can imagine. Shock of 
shock, but people do learn. Pokeman cards used to 
be the in thing. Some were worth $150! Now kids 
are running away from them. You can't blame them 
for that either.