Gotta love this one. Its cheap, simple, and can work on any car, basically you get 4 of the suction cup holders to act as standoffs on your roof, and then tie down the load thru the doors with ratchet tie-downs (which you would do anyways, well maybe not thru doors). The suction cups run around $8 each, and you can get a free flashlight and 20% off with coupons.
http://www.instructables.com/id/DIY-Dual-Cup-Suction-Lifter-Temporary-Car-Roof-Rac/