You need to specify what brakes are used on your coach. I think you probably have the Bendix ADB225 disc brakes. There will be a staming or tag on the calipers.
If so, here is a link to the price for replacement brake pads... https://www.anythingtruck.com/product/060-802593.html
Regarding rotors, there is a minimum thickness allowed. The rotors can be cut ("turned") to remove shallow cracks and warpness - to a point. Before replacing them, see if they can be machined.
This is a replacement rotor for the ADB225 (but you need to verify if it is the correct one for you) - but for an idea of pricing... https://www.anythingtruck.com/produc...531802081.html
The picture below is for my coach (2005 model year) which has the Bendix ESD225 brakes). If that is what you have, then the part numbers are shown on the picture. One way to tell is that the pads are held in with a strap and bolt on the ESD, and the ADB style uses a strap and a pin.