Real Time Air Speed or post flight
AirSpeed,
That would be a reasonable readout. Sounds similar to the way error storage is read on autos. It takes a little practice to learn but it's not too hard and would simplify and keep light the whole thing.
What price target would you be aiming for?
Will it require a pitot tube?
Would it be self-powered to facilitate easy locating and mounting?
I'd be willing to pay around $30 for an item like that. What do you think of an on-line survey to see what people would be willing to pay? That might dictate the design.
I hope you pursue the project. It would fill a gap which has no competitors. The whole area of instrumentation, i.e., acceleration, speed, altitude, etc. has not been exploited.