The Make blog has a post on making a Pietenpol Air Camper (shown above is the G-BUCO, a nice example built by Alan Reading of Reading, Berkshire, England) for $2000. Bernard Pietenpol from Minnesota made his first homebuilt airplane, the Model T engine powered Sky Scout, in 1923. In 1929 he built a Model A engine-powered two-seat Air Camper and showed it to the editors of Modern Mechanics magazine, who subsequently published plans. Bernard improved the design, and, in 1933, published new plans, which are still available from a web site run by his son and grandson. Air Camper plans cost $100.
I’m not sure where Make got the $2000 figure: the Pietenpol web site notes that “for about $9111 (2008 dollars) and a lot of scrounging plus 1000 hours of free love construction time a pilot can be in the air.”
Chuck Gantzner’s web site has tons of details and pictures about the building and flying of his Pietenpol, the NX770CG. Being a true Toolmonger, he built the wing in his house (wing top and bottom during fabric covering shown below).
The Pietenpol family website also has lots of great pictures, including several oldies from the late 20’s and early 30’s.