7.4V RC 2S Battery Balance Charger (Banggood, Aliexpress: Input Voltage: DC 5V 1-2A, Product Name: 7.4V USB Charging Cable, Weight: 18.7g, Output Voltage: DC 7.4V 800mA (the best price with coupon)).
Go down and check coupons out. Remember to check price history if it is available. You probably want to know what is the best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
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. Well, there is one coupon available right now.
Link: Banggood product page
1. ($8.49): BGRCParts8
just apply this code 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/feV
Old coupons (from the oldest to the newest): AFfbG10, BGBFAFF2019, BGCITYADS2019, Parts8, BGVDay10%off, BGAFF10OFF, bGhOnEy10, BGdragonBoat, BGSS10%SW, BgoFErTaSchInA10, BgcLuBofErtA10, BGDAVIS, BGHONEY2110, Tabby20, BG1efeb0, 8Couponsde, MVC8SPRING
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Price history (for all/most countries) for 7.4V RC 2S Battery Balance Charger is here. The lowest price was: $2.33.
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)).