Lexus SC430 :: Unstable On Highway Or At Speeds Over 50mph - Lower Control Arm Bushing Gone?

I am having an issue with the car not feeling stable on the highway or at speeds over 50mph when I am on a curve and go over a roadwork patch. The cabin of the car seems to float way too much to the side, almost like hydroplaining although the wheels stay put on the road.

After describing this to a mechanic, he said it sounds like my lower control arm bushings are gone. He looked at them and confirmed it, the rubber bushings that control the side to side action are cracked and worn out. He said that he is unable to just replace the bushing and has to special order the whole arm from the dealer (approx 200$ each arm).

I went to get a second opinion and another mechanic basically told me the same thing except the price on the part went down to 175 per arm with 2-3 hours labor.