Skid Control Component Pricing Help

My dealership just called and said my 2007 Prius with 155,000 miles needs a skid control component for $1,600 and a right front speed sensor for $240 but feels very certain this will fix the car. Does anyone know where I can get a cheaper but reliable skid control component?

The dealership also said my main battery will probably die after about 50,000 more miles or more and costs $3,000 to replace and install.

The original problem:
I would drive the car about 30 miles or more and then warning lights ((!)) and VSC would come on. About 10 miles later, the car would max out at 38 MPH and the main battery gauge on the display would turn purple. After 3-6 more miles, the main battery gauge would drop to one bar and the transmission would only go from Park to Neutral. I turned the car off for about 20 minutes and it restarted and ran just fine for a while and then the problem reoccurred. I took it to the dealership.

Thanks for any help, advice, and suggestions.
- George

 

I called the dealership back to clarify and they said I need the skid control computer, part # 89540-47130. I did a google serach and didn't see one that exactly matched the last 3 digits of that part number. Opinions and experience anyone?