How much is 5000 Estados Unidos Mexicanos dated 1938-1988 with a dollar sign in front of the 5 and an eagle holding a snake on the back worth in US money?

Due to a 1992 monetary reform in Mexico that made 1000 old Pesos equal to 1 New Peso the 1988 5000 Pesos is worth about .50 in the U.S. (1 Peso = ~10c U.S.). You might also try a library for a copy of the Standard Catalog of World Coins for pictures, values and lots more interesting info.