Silver dollars are American $1 coins. Not always of silver, they may be made of almost any white metal alloy. Older versions tend to contain more bullion. The coin's value is based both in the amount of actual bullion it contains and on the rarity of the particular silver dollar issue. Silver dollars have featured images ranging from American Eagles and Lady Liberties to portraits of Sacajawea and Susan B. Anthony.
Determine the absolute minimum value of a silver dollar by finding the value of the bullion contained in the coin. Bullion means the actual precious metal in the piece: gold, silver or platinum. Check a site like Canupnet to find out the bullion content of different silver dollar issues. You will see both the weight and percentage of the precious and base metals. MONEX and other commodities trading organizations feature current prices for gold and silver in troy ounces and grams.
Visit a collector site, such as CoinFacts.com, to learn about various issues. Silver dollars were issued in varying numbers over the years. Sites like CoinFacts give the number of coins in each minting, years minted, as well as pictures and information about proofs. Proofs are especially fine coins that are made in smaller numbers with special dies.
Take your silver dollar to reputable dealers. Compare prices if necessary. You can sell your silver dollar online or at an actual auction. Sites such as Heritage Auction Galleries will show you sales information from previous auctions that will permit you to make more informed decisions. Prices will vary according to dealer and current market conditions.