Any reputable website will show the market price for silver. Armed with that knowledge, you can buy silver anywhere and not get ripped off. If you buy at your local coin shop, you won't have to pay shipping, but pay for gas to get there.
http://www.apmex.com/category/503/silver
http://www.kitco.com/
http://www.free-bullion-investment-guide...
Silver coins are negotiable (because they are "collectibles") so you just need to shop around...but just "silver" is a commodity, so the price is (basically) the same everywhere...check who has the lowest commission charge in YOUR area....
Look up a reputable coin dealer in your area. I've worked with a couple and they have always been honest.
Everybody goes by the "spot" price plus a mark up / mark down when selling / buying.
The variance will be very small from dealer to dealer.
hate to be one of those 'link somwhere else' guys but there is *always* hearty discussions about your Question over at Zerohedge website - check the discussion sections under any topic that mentions precious metals.
coins and silver