Looked at the $40 one's, but didn't want to drill 4 holes in bumper. They also are rather large compared to factory installed. If my car was black to match sensors I would have give it some thought. Did you have yours painted to match car? Some won't work if painted over! The Ross type are microwave sensing. They see through the bumper, so are hidden. I don't think I was ripped off for this type installation. A local auto store wanted $325 for same. There are all kinds & prices, this is another option which I am so far happy with!