Silver American Eagles. Why is the price so high?

Why is the price so high ? I have noticed a steady increase in price over the market spot price. For a long time the availability was steady and abundent. I never had a problen locating the coins. The price on ebay is just to high. I can't find any in local coin shops.

Is there a shortage of product ? Is the spot price wrong ?

On the link provided below is a list of Silver American eagles. If you follow the coin links you will see an ebay price.

http://www.worldcoindata.com/American%20Silver%20Eagles/AmericanSilverEaglesIndexPage.htm

Please post a comment if you think you have an explanation.

Thanks