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Tom Boblittbut just be careful if what you're sending is not replaceable.  A PSA5 T206 Cobb is pretty replaceable.  You might call their general customer service number to check it out.  I don't know Fedex's.  I'm sure it's on their website.  UPS's is 1-800-pick-UPS.  
I think Mastronet insures most all their stuff outside of the carriers they use.  They get riders on all the large items and the lower value stuff is covered under a blanket policy probably.