What is the value of a 1949 South African 5 Shilling coin?

You are asking about a 5 Shilling coin (also called a "Crown") from South Africa (KM#40.1). The coin weighs 28.28 grams and is 80.0% silver, giving it an ASW (Actual Silver Weight) of 0.7273 troy ounces. With silver at US$18.50 per troy ounce (as of June 1, 2010), the "melt value" of this coin is about US$13.46.

The obverse of the coin has a portrait of King George the Sixth and the words "GEORGIVS SEXTUS REX" (Latin for "George the Sixth, King"). The reverse has an image of a Springbok (an African antelope), with the words "SOUTH AFRICA", the date, and "SUID-AFRIKA" (Afrikaans for "South Africa") above and the denomination ("5 SHILLING") below.

535,000 of these coins were produced in 1949. According to the 2010 Standard Catalog of World Coins, an example is worth about US$13.50 in Extremely Fine condition and US$20.00 in Uncirculated condition. Given the current price of silver, however, the actual numismatic value of these coins is probably actually a dollar or two higher.

Another 2,000 were produced in Proof-like condition - these are valued at about US$35.00 each; and 800 were produced in Proof condition - these are valued at about US$50.00 each.