https://comparesilverprices.com/ One of the things I noticed was the significant price differential between Provident and Apmex on the 1 & 10oz size coins/bars. Edit to put up the companion gold site https://comparegoldprices.com/
Are the prices for the included dealers current to the minute, day, week? What if a dealer decides to run a special sale on ASE's for example next hour, will this site reflect that? How soon after the sale has begun? .
I've always found that JM Bullion has the best prices and Provident is a solid runner up once you factor in shipping costs. I don't bother with Ebay though, and you'll have to factor in the risk/reward advantages and disadvantages of using it. Obviously, reputable dealers and mints have storefronts on there, but I'm not buying in bulk anyway so I'd probably not have much chance of getting significant savings from auctions or flash sales.