I've had mixed results with hitches on my Acura MDX. When I first got the vehicle I went with an aftermarket hitch made by Hitch-tite - a well known hitch maker for just about all manufacturers. I think I paid $120 including shipping. I installed it myself, which is pretty easy if you have a friend help you. Essentially, the hitch bolts right into the chassis frame using 6 bolts and the car frame is pre-threaded. But, I found that once in a while, the muffler would make contact with the hitch while driving, sending a vibration noise through the car. It drove me nuts because the muffler and hitch didn't touch when the car was standing still. They only made contact at certain highway speeds. Apparently, the exhaust system moves on those rubber support clamps more then I thought. So, I just lived with it for a couple of years.
One day while driving to CR, I was rear ended by someone. Believe it or not, my Thule T2 rack survived unscathed, but all the energy was absorbed by the hitch, which was bent to the point that it made contact with the muffler 100% of the time. The lady who hit me offered to pay for the replacement hitch, so I had it replaced with a hitch from Acura, and there is no contact at all with the muffler anymore and no noise either.
Moral of the story: The aftermarket racks are a fraction of the Acura price but just make sure that others have had success with the brand of rack you are looking to buy before you take the plunge.