What is the value of a 1987 Canadian Dollar?

Assuming you mean a gold-colored "Loonie" coin that's the same size as a U.S. Sacajawea dollar, it's a regular circulation coin and is worth face value only, 1 Canadian dollar

If it's a larger silver dollar it's a collector's bullion piece worth a premium for its silver content. The 1971 - 1990 are only worth about $10 - $13 each. 1991 through the present range from about $15 - $45 depending on the year.