We may end up doing some for both 1/20 and 1/24 but it's not just a matter of scaling parts. There are some differences in the hubs and rotors between different cars and especially different eras. So some parts would have to be redesigned to suit the newer 1/24 cars.
As for price, machined parts are expensive to have done. The cost of having 1/24 or 1/20 parts made is actually not much less than having 1/12 parts made. The cost is in the machine work and the actual material cost is only pennies per part. So there is no way we could do a set in turned aluminum for $20. Keep in mind the set would include turned rotors and hubs. Turned axels with working wheel nuts so the wheels could be removable. We would likely include cast resin calipers of the correct type so you wouldn't have to cut apart the kit brakes and risk damaging them and being left with no calipers at all. We might also include turned aluminum valve stems. The rotors themselves would have to be machined and then have something like 35 holes precisely drilled in them. The hub faces would be machined and again have something like 16 or 18 holes precisely drilled in the face. These are complex parts so the costs are high to make them. It's an investment of many thousands of dollars to have a run of a single set made for one or a few cars. So we could conceivably do a set for the F2000 and F2001 and maybe one for early McLarens etc. But we will likely have to do them one at a time.
It's all just at the stage of research and talking to the machine shop right now so nothing is written in stone.
Regards,
Ron
Racing Miniatures
www.racingminiatures.com