Just check coupons out (with price alert and history). Best price?
Pack wight: 600g, Voltage range: 0.2V-5.0V @1-4S, Product wight: 450g, Product size: 150*112*36.5mm, LCD: IPS 3.5inch 480*320pixel, MicroUSB: Upgrade@USB2.0, Pack size: 160*160*46mm, Internal resistance: 1-100mR @1-4S
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):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($90.98): BGGAL8
2. ($90.98): BGRCParts8
3. ($90.98): BG8RCToy
4. ($90.98): hoNEYbGdeAlS
apply it in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGTT10, BgcLuBofErtA10, BG11M4Q1, BGM4Q1, BGM4Q2, BGJPM4Q1, BGM4QJP, 1756670, BGAFF10OFF, BGM4QCNY, BGJPTK1291, BGJPM4Q2114, BGM4QSP, BG3M4Q, BGCuponation10, BGmatteo87, BGM4Q316, BGBCSpring1, BGM4Q3, BGM4Q4, BGDAVIS, BGHONEY2110, xollodrnes15, BGM4Q12, BGM4Q76, BGM4Q78, Parts8, BGM4Q908, BG11M4Q1PL, BGM4Q1109, BGRCBC11, BG11M4Q11, BGissam1010, BGSFBC1, Tabby20, BG1efeb0, MVC8SPRING, 8BGwbg2204, BGJPM4Q04, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN
(these codes were not working in latest coupon update, but you can check them out anyway)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – ToolkitRC M4Q 4x50W 5A 100W Balance Battery Charger [EU] ($-3)
Price history and price alert
Price history (for all/most countries) for ToolkitRC M4Q 4x50W 5A 100W Balance Battery Charger 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)).