Doppler shift velocity sensor
I suspect that a Gunnplexer as used in Police RADARs and in door openers prior to PIR's taking over would do what you want. Output is Doppler difference of go + motion affected return signal. 

!

A few examples:


Amateur use, 
Treasure! Gunnplexer cookbook 
ARRL - overview only
The Bees Knees! - price unknown but liable to be too costly
Through wall motion detector but cited due to Vast range of potentially relevant references