Hey Drac,
I see this kind of thing all the time.  When 
selling things that I think are way valuable, I 
will usually insist on insurance, it's only 2 
bucks most of the time. If the person buying the 
item doesnt want the ins. because they have to 
pay 2 dollars, then I say it's their risk to 
take.  Now, this is only for expensive cels that 
I do this.  Most of the time I dont even offer 
it.  I just get tracking or something.  
I do think you should word your phrase a bit 
different.  After the parcel leaves your hands, 
it really is not your responsability after that.  
Insurance cant really stop the package from being 
damaged.  I havent had anything get to a customer 
yet that was damaged, so I dont know how to deal 
with it really.  I did get a damaged item once, 
thank God it wasnt a cel, but I was a bit 
miffed.  Ahhh, what can you really do?  If an 
item is very expensive or rare, like, over 100$ 
then I think isnurance should be a must.  If 
anything for peace of mind :).  Bye, and good 
luck!