Aliexpress
Click here… to search for Solar Power TPMS with 4 External Sensors on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (28.15 USD): BGSCM75
Coupon (29.11 USD): Cuponation9
Coupon (29.43 USD): BG8ReviTrage
(CouponsFromChina.com tip: put item in your cart and apply coupon code there after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): 8BGwbg2204, tRaDetRaCKeR, BGAUTO22, BGdcbfa8, 9OFFSUMMER
(these coupons are old, so probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for Solar Power TPMS with 4 External Sensors.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).