I've got an option that no one has yet offered. About 15 years ago use of an escrow service was how we protected against shady sellers for online deals. It has fallen to the background these days as people think their losses will be covered by Paypal, Ebay etc. I suggest looking into:
www.escrow.comThey're a reputable service and the only authorized service for Ebay. Basically the buyer and seller register, agree to terms of the transaction. The buyer pays to the escrow, the seller gives shipping confirmation. Once received and the item is approved by the buyer the funds are released.
Of course there is a fee involved but I think it is very reasonable exepcially for more expensive items. Plus it's going to make a seller think twice if he's trying to pull a fast one.