Out of the choices of Cheep, Quick and Good, you usually only get to pick two. This project satisfies all three goals of most of my projects. I needed to lug home some 1/2" sheets of fragile yet flexible 4' by 8' drywall with only my Honda Civic. I built a roof rack that will allow me to haul 4 by 8 foot sheets of plywood and drywall. It is easily torn down to re-use the lumber or adapt it to a different car. The lumber for this project cost $10.
http://www.instructables.com/id/Drywall-and-Plywood-Cartop-Carrier--Roof-Rack/