Can't think of any instrumentation that could easily be made to work cheaply. Presumably something that integrated rate of descent/TAS/engine power information electronically could be made to work but would have to be individually calibrated to a particular type and I'm not sure whether weight might have to be considered as well.
I do remember a presentation a long while ago on a pitot system where the intake aligned itself with the relative airflow and presumably could indicate when the inflow was reaching a critical angle.
Personal experience: Helicopter camourflage trials in the desert, landing with different backgrounds and on specified headings unrelated to wind direction while the fighter recce guy rushed past taking photos. Got bored after about the 10th and didn't pay attention to the downwind component. Classic VR, R of D increasing, raise lever, ground coming up, oh s..t, no airspeed. Fortunately ground fell away to the right into a wadi, so was able to stuff the nose down, roll right, gain some airspeed and just graze the brown bits. Comment from the jet jock, "can we do that one again, it looked interesting". Get stuffed!