Power: 1500W, Speed: 15000 r/min, Flow Load: 4 L/Min~8L/min, Battery Capacity: 15000 mAh, Material: ABS Plastic, Compatible Battery: For 18V Battery, Pressure: 30 Bar~60 Bar, Charger Voltage: AC 110-220V 50/60Hz, Outlet: 1/4″ Quick Connect, Battery Voltage: 88V, Optional Pattern: Without Battery SET/1 Battery SET/2 Battery SET, Outlet Pipe Length: 5M.
Basically copy coupon, view price history or create e-mail price alert. What is best price?
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.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. There is one coupon right now! Check this out.
Link: Banggood product page
1. ($13.59): BGPTL088
just apply this code in your cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
Price history and price alert
Here is price history (for all/most countries) for 88VF Car Washing Water Pump with 2 Batteries. The lowest price was: $13.59.
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)).