If you go to the Ambient web site and sign up for their email notices, you will occasionally get alerts of sales.
For example, on Tuesday October 19th (a week ago), they announced 15% off for the WS-1900A and WS-7079 packages when purchased on Amazon, pricing good through the end of October. [I bought a new WS-1900A just for the Osprey array.]
And on Thursday October 21, they sent email announcing a sale on various WH31 sensors directly on their website, using code SNSRSZN, pricing good through 10/26/2021 (today!)