What is the value of a 2 headed 1972 silver dollar?

This is a magician's or novelty coin, manufactured from two regular coins. They can be bought or sold for around $3-5. Because they did not leave the Mint in this condition, any collectible value the 1972 dollar may have had is negated by the modification. 2-headed novelty coins are usually made from the smaller denomination coins, like nickels and quarters. A 2-headed Eisenhower dollar is actually a bit rarer. These generally sell in the $15-$20 range.