$3,000 or $4,000.
Folks will pay that much for them if they have and advantage.
I have a set of brakes on my road bike that are worth $4,000 to $5,000 (I did not pay that much new, but they were $500 at the time which was 3 x the cost the next best brakes).
There’s only so much speed you can buy. I don’t see many pros running the 454 Zipps.