Current Melt Value Of Coins - How Much Is Your Coin Worth?
is good for circulated coin pricing (melt prices) but really wont do what I think you are looking for...
I am not familiar with a site that quotes everyone's sale prices. It would be nice to have when buying pms but I just have the companies I buy from bookmarked. It only takes a few minutes to calculate shipped cost on whatever I'm buying from three different sites and go with the cheepest that day.
Modern Coins, World Coins, Silver Eagles, Gold Buffalos, Bullion | SilverTowne
APMEX | Silver, Silver Bar, Silver Bars, Silver Bullion, Gold and More - APMEX.com | APMEX.com
Buy Silver Coins, Silver Bullion and Buy Gold | Gainesville Coins
are the three I have bought from so far
Hope that helps.