I'm interested in developing a trackball for retail sale to the assistive technology market (users with disabilities). I'm looking for some ideas in terms of contracting someone to do the PCB design and the code for an optical trackball. I have the facility to product the physical components (housing and ball). In particular I'm wondering about how developers set up contracts - do they provide an estimate and then perform the work? What sort of protections are there for both parties in terms of the quality of the work etc?
If anyone could recommend som resources I'd be interested to hear more.