The R107-generation Mercedes-Benz SL roadster, built from 1971-89, is one of Mercedes’ most iconic cars. It’s more timeless than its successors; it’s also, by classic car standards, cheap. Mercedes sold more than 200,000 of them in the U.S., and many of them spent pampered lives as weekend cars. You can spend more than $20K on one, but you can also find one in reasonable shape for under that.