I'd guess an easy $1 Billion for the project.
Related reading for a plane with a system similar to the proposal:
https://www.atsb.gov.au/publications...ir/ao-2015-149 An Australian report on a 787 incident. It illuminates some design trade-offs made for such systems.
Curiously the 787 only does synthetic airspeed, not AoA.
A full SADS (Synthetic Air Data System) looks expensive.