You can get 4000mAh 150PSI Portable Car Air Inflator for $26.99 with coupon (from Banggood). Price history, coupons and price alert are available on this page. You probably want to know what is the best price?
Latest coupon and price update (UTC):
4000mah 150PSI Digital Display Portable Car Air Inflator Motorcycles Bicycle Tyre Wired Inflatable Pump
Banggood ($26.99)
Banggood warehouse is located in China. There are no active coupons for this product, but the price is pretty low isn’t it? Is it a low price? The average price for this item is $27.49, so I think it’s a good price!
Link: Banggood product page
Price: $26.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BG4a2ae1, BGLMQ15, BGSCM11, BGAMMT03
(you can check these old coupons out, but these probably won’t work)
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
Check out price history chart (for all/most countries) for 4000mAh 150PSI Portable Car Air Inflator.
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)).