Fret, it sounds like you found a good buying dealer. I think it's a lot like this: Dealer1 buy's low and sells low. A good spot to buy your coins at if graded correctly. Dealer2 buy's high and sells high. A good spot to sell your unwanted coins. Rarely do you see anyone around long that is a good place to buy coins and sell them both at a good deal as that means there no money for their store costs.
I just read the poll results and see that over 25% of us think the dealers should make less then 15%. I find it funny that most servers at restaurants get more then that for just delivering food to a person but if a dealer is delivering your coins you feel he should make less. Oh yea and he has rent, electric, security, insurance, tax's, license ect...