However, I think that the real problem now is that currently if someone would make this device is forced to buy the same expensive TPMS kit that I've used in my project.
The best thing would be to make an agreement with the manufacturer in order to buy only the tire sensors and a receiver module ready to be applied on my hardware, or best, to entrust to him the whole build of the preassembled device. Certainly this would be more cheaper.
So if someone are interested in do this, is free to use my project, my only request is to leave me the sales of the PIC with the firmware inside.
Otherwise if someone is interested in self made it, I can sell to him the programed PIC.