I feel the same.  I try to stay as close to what 
I paid as possible.  The only increasing I like 
to do is to add the shipping that I paid.  Of 
course, I have to admit, sometimes I honestly 
forget what I paid for a cel.  I tend to try to 
go with general market values at that point.  And 
if someone offers me an insane price for a cel, I 
may have a difficult time telling the person no.  
But then again, I have never been in that 
situation!  But $600 markup - EEK!  
Jenn:)