Necessary to replace brake fluid actuator pump?

My 2007 Prius (151,000 miles) just started making what sounds like a scraping sound when in motion. This does not happen every time I drive it. The dealership said I need to replace the brake fluid actuator pump. He quoted the cost of the part as $1,900; with labor, the total repair is $2,500.

Has anyone had this repair done? He couldn't really tell me what would happen if I don't have it fixed. He said perhaps the power brakes would go out, or maybe the anti-lock brake system. Either way, I don't want to mess with possible brake failure. But the cost of this repair is so high, and my car already has 151,000 miles. I'd love to drive it to 300,000 miles if I can, but am I being realistic? I'm wondering if it's worth investing this much money in a car with so many miles.

Your advice is appreciated!

 

No, there is no warning light. In fact, the car isn't making noise anymore. I had the brakes and tires checked and they are okay. I'm considering not doing anything right now. I'm going to at least get a second opinion.

 

That's what I'm thinking. I live in Chicago and we just got a huge snowstorm over the weekend. The car was a mess with ice, dirt, etc. I'm thinking it could have been debris.

Thanks for your advice!