According to my DB the lowest price is $82.79 for QX-Motor Underwater Brushless ESC Waterproof 2-6S 120A (in Banggood). Just check coupons out (with price alert and history). Best price?
QX-Motor Underwater Brushless ESC Waterproof 2-6S Two Way 50A/70A/90A/120A w/ BEC for RC Boats Submarines Vehicles Models Parts – 120A
Latest coupon and price update (UTC):
Banggood ($82.79)
Banggood warehouse is located in China. You probably want to know if this is a good price. Maybe there’re no more promotions for this item, because current price is higher than average (which is equal $77.49) There is one great coupon!
Link: Banggood product page
Price without coupon: $82.99
1. ($82.79): BGALL8
paste coupon code in your cart and click Apply 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
Old coupons (from the oldest to the newest): BGbd7384, BGESJY8
(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
| Image | Product (link) | Price | Coupons |
|---|---|---|---|
 |
Underwater Propulsionr QC2221 with Waterproof brushless Motor 6S cw ccw optional 50A ESC For RC Remote Control Ship Model | $47.21 | – |
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 QX-Motor Underwater Brushless ESC Waterproof 2-6S 120A 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)).