Glad someone understands economics lol... because yeah, that's precisely why anyone charges a given price for anything: because someone will pay it. If nobody's willing to pay it, they'll drop the price. That being said, if you're buying silver for the sake of investing, you should avoid retail outlets for such things. You're never going to come out ahead there. Retailers buy silver at about melt, so for them to make a profit, they have to sell it for more than that.
take a look at how much the fees are to sell on amazon. Much higher than ebay when it comes to coins & collectibles