I think the obvious answer is e-bay. I don't know about all the fees as a seller, but as a buyer you generally can't touch even the most worn-out 90% silver coin for anywhere close to spot. It's usually as much premium as you'd pay to buy fine silver 1 oz rounds.
So if I was selling silver coins, I'd probably put them on e-bay!
Ebay, and PP combined cost seller in the order of 15%, you should easily do as good as that at ANY reputable coin dealer / coin shop, AND save yourself a lot of pain. In fact that's why I could never figure out why people sell common date silver coins on there one at a time, with all the keeping track, going to the post office, waiting for some to pay you, etc. etc.
Anything to the contraption they advertise that turns your microwave into a smelt furnace? Question here is there any advantage to melting and selling yourself?
Most of what I see on ebay goes way over 15% over spot, even for totally trashed 90% silver with no numismatic value. I doubt you'd get a coin shop to give you that much. Best to shop around though!