You can check the price of an oz. of silver on a minute by minute basis at;
kitco.com
At the site, scroll down a bit, it's on the right.
The price shown is called the Spot Price and is used for buyers and sellers to set their own price. If you are able to buy silver at the current spot price, that is considered a very good deal. Keep sales tax in mind if purchased in your state and S+H if mail ordered.
It is common to pay up to $1 per oz. over Spot when purchasing and receive $1 under Spot when selling to a dealer. Any amount more than that means you could probobly find a better deal elsewhere.
Pre 1965 American coins are 90% silver so for example a 1964 silver dollar is really a silver dollar.