$97.99 – WIFI GSM Alarm System Kit (Banggood, Aliexpress: WIFI GSM Alarm System Kits Tuya Smart Home Wifi Door Sensor Doorbell Motion Sensor/Detector Security Alarms for Home (the best price with coupon)).
When I was updating this page, then coupon price was $97.99 for WIFI GSM Alarm System Kit (in Banggood). Basically copy coupon, view price history or create e-mail price alert. Best price?
Latest coupon code price check (UTC time):
Banggood ($97.99)
Banggood warehouse is located in China. Hmmm… There is no active coupon in Banggood at this moment. Is it a reasonable price for this item? From what I can see this price is higher than average price ($91.57).
Link: Banggood product page
Price: $97.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/feV
Old coupons (from the oldest to the newest): BGAUGUST8, BGCAPITALOS8, BGCOUPERT8, BG8FORMULAMX
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. Here are coupons that you can use.
Price history and price alert
Check out price history chart (for all/most countries) for WIFI GSM Alarm System Kit. The lowest price was: $90.15.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).