Just check coupons out (with price alert and history). Best price?
Balanced Cells: 6S, USB Output: 5V/1A, Input Voltage Range: DC 10~27V, Package weight: 90g, Product size (Lx Wx H): 78X55X18mm, Model: H605, Output Current Range: 0.1~5.0A, Maximum Charge Current: 5A, Balance Current: 250mA, Output Voltage Range: 0.5~28V, Max Charge Capacity: 50W, Package size (Lx Wx H): 90X65X25mm, Product weight: 68g
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 code price check (UTC time):
Banggood
Banggood warehouse is located in China. There is one great coupon!
Link: Banggood product page
1. ($35.05): BGGAL8
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/5cd
Old coupons (from the oldest to the newest): BGSKUA73500, BGH6051, AFfbG10, BGBFAFF2019, BGCITYADS2019, BGH605, BGVDay10%off, 0e7f33, BG10BC, BGAFF10OFF, bGhOnEy10, BGISDTH605, BGBC1, BGdragonBoat, BGSS10%SW, bgshOOp10, BGRC902, BgoFErTaSchInA10, BgcLuBofErtA10, BGCuponation10, BGBCSpring1, BGDAVIS, BGHONEY2110, Parts8, BGRCBC11
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for ISDT H605 Air 50W 5A 2S-6S RC Battery Charger.
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)).