I agree...'bogglingly low' is a good term. I 
also had someone email for one of my last 
unicorn cels.  It was a production cel with 
matching production background and a sketch.  
The combo of all three is INCREDIBLY rare and I 
paid well over $1k for it.  They offered $150 
and found *ME* insulting for not accepting their 
offer b/c after all it was 'just a piece of 
acetate.'  I'll never forget that email.  It was 
a good laugh.