Are Audio Dealers Missing the Boat?

I was wondering if dealers could be earing some $$$ acting as the middle-man in audio trades? The seller could bring the item to a participating dealer (listed on, say, Audiogon?) who would test it, grade it, verify its condition with the buyer and ship it for a fee?
I'd be willing to pay 10% for this service. The dealer could earn even more by allowing credit-card payment (sorry pay-pal).