You can create price alert here, copy coupons and view price history. Let’s see what best price is ATM.
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Pressure: 2 (Mpa), Traffic: 12 L / min, Impeller suction method: single suction, Conveying medium: oil pump, Motor Speed: 8700r / min, Pump shaft position: horizontal, Performance: no blockage / corrosion resistance / wear resistance, Head: 2 (m), Model: 679917, Uses: submersible pump, Voltage: 12V, Drive method: electric, Size: 140x38mm, Number of impellers: 6, Material: Stainless steel, Material: Aluminum alloy, Maximum Load Current of 1.5A, Flow rate: 1900 (m3/h), Model: YB-38, Color: Silver, Principle: Vane pump, Brand: other, Pump Diameter: 38mm
Banggood
Banggood warehouse is located in Europe 
. Sorry, but there’s no price history in my database. There is one coupon right now! Check this out.
Link: Banggood product page
1. ($13.19): BGSCM11
this code has to be applied in your cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
There were country-specific coupon codes published on Couponsfromchina social channels and price alerts. Coupon price may vary by country, because there’re different VAT rates, shipping cost etc. There is a chance that some latest coupons are still working:
Old coupons (from the oldest to the newest): BG2bb4b4
(probably won’t work, but you can try them out)
Price history and price alert
It doesn’t make sense to generate price history chart, because there is one price record which is: $12.99.
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)).