I really don't think that you should worry about 
emaily low offers.  I often get offers that are 
quite a bit below what I paid for them.  But 9 
times out of 10 its someone who is new to the 
hobby and does not have a feel for the market.  
I just write them back with what I would like to 
get for the cel, or if it is even available.  I 
like knowing that there are collectors out there 
that appreciate my cels.

Its the rude SOB that writes back telling me I'm 
crazy if I think ANYONE would pay that price.  
And while I'm at it, I should just sell them the 
cel at the price they suggested.

You see, it's the rudeness that makes that offer 
insulting.  Not the price.
 
But that's just me.