This is a topic that I have ranted about to 
many an anime fan...
A few months ago when I bought a cel of Princess
Ilina from Nichibei (they were wise enough to
get insurance on the cel) it arrived in *horrible*
condition. Both the top and bottom of the package 
was so badly punched in that it looked like some 
screwup at the post office used it for a discus. 
Luckily the cel was mutilayered and had clear 
portions at the top and bottom, so the only 
sections that were cracked and broken did not 
contain any paint.  

So of course I would say that insurance is a good
idea. Sometimes I think the Post office just 
isn't careful with packages, and they need to be
held accountable for that.