I have checked all old coupons and price is $7.99 for 0-200Psi Digital LCD Tire Air Pressure Gauge (in Banggood). Price history, coupons and price alert are available on this page. What is the best price?
Diamter: 58mm/2.28in, Material: metal, Display: digital, Four kind of unit: PSI KPa Bar Kg/cm2, Product name: LCD Tire Pressure Gauge, Interior Battery: 2xCR2032, Measure scope: 0-200PSI, Main color: black, Fitment: universal for most vehicle;such as car /truck /van /motorcycle etc., Working temperate: -20°C to 80°C
Latest coupon code price check (UTC time):
Banggood ($7.99)
Banggood warehouse is located in China. Too bad there’s no coupon right now in Banggood. Price? Cool, average is $8.70, so current price is lower!
Link: Banggood product page
Price: $7.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGSCM11, BGe8a594, BGc1ab77, BG599541, BG6bd1b4, BG16217e, BGeb34c8, BGCAR639, BGAMMT03, BGad2fc9, BGe5d8db, BGea768f, BG5c10a8
(system checks these coupons on every price check (like once per 24 hours), but you can check them out anyway)
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Price history and price alert
Price history (for all/most countries) for 0-200Psi Digital LCD Tire Air Pressure Gauge is here.
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)).