Last summer, while towing a travel trailer a rear sensor failure caused my 2006 to lean to the right by about 3". When I started reading about repair costs and the almost certain failure of the remaining system, I decided to change out all 4 wheels for under $300. I don't know much about the various sources, but after reading reviews, I went with Suncore. The struts seem well made and sturdy. After about 6 months, I am very satisfied and happy that I am not worrying about the uncertainty of the next failure. The ride is definitely stiffer, but not bad, and I have to deal with the warning "suspension turned off" which you have to clear every time you start a trip. There is an electronic fix (about $100) for the warning light, but it's really not a problem to hit the reset button every time I drive. Suncore does offer a rebate core charge, but it is only about $50 for the whole set. I saved the shipping boxes and they sent me a prepaid shipping label.
I was sad to find that my air suspension would not last and would be potentially very expensive. Sorry to lose the excellent ride, but I don't regret the decision. Still tows my 7,500 travel trailer fine.