Your best bet for JC cels is looking at other 
prices on the web.  As for Dual it is a little 
bit harder seeing that you don't see too many 
cels from Dual.  (there are bunches on ebay) all 
for around $20 bucks.  The most I have paid for a 
Dual cel is about $60 and it was of "d".  The 
others I get for about $20-$30.  I would not go 
too much higher, unless it is a great have to 
have cel.  

I am not too sure if that helps you out at all. I 
hope it does.

Third-child