Ed C sends us the $135 “Skateboard Car” - the 1915 Smith Flyer (later the Briggs and Stratton Flyer) - a bare-bones, ultra-lightweight vehicle built of two wooden planks and 20-inch bicycle wheels that utilized a powered "fifth wheel" on the rear, essentially making it a motorized skateboard. The Smith Flyer was powered by a single-cylinder, one-horsepower engine attached to a fifth wheel, eliminating the need for a clutch or complex gears - providing a top speed of 22 miles per hour.
More pics and information here