clip on (or screw on if you are ok with permanent) yakima/thule car racks plus a car box? Ours are clip-on (it hooks into the door jams), so they are completely removable. We have a car box attachment and a bike rack attachment for the racks. The racks and box were ~$650-700, so much better than your quote. My parents have used the permanent racks for years, and they just always installed it themselves (approximated the rack placement pretty well and then went at it with a drill, no issues)
we have a tiny car (chevy prism) and we use the clip-on rack + box setup to go camping with LOTS of gear, plus skiing/snowboarding/biking/canoeing/other activities with gear that wont fit in the car itself. Essentially, add additional, external storage and you should be good to go.