$9.23 – 5x JST Connector Plug RC (Banggood, Aliexpress: Quantity: 10 pairs, Length: 15cm (the best price with coupon)).
You can get 5x JST Connector Plug RC for $9.23 using coupon code (in Banggood). You can create price alert here, copy coupons and view price history. Best price?
Latest coupon code price check (UTC time):
Banggood ($9.23)
Banggood warehouse is located in China. I don’t think there is an active coupon right now – at least in my database. What about the price? Maybe there’re no more promotions for this item, because current price is higher than average (which is equal $2.29)
Link: Banggood product page
Price: $9.23
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/feV
Old coupons (from the oldest to the newest): aff7off, rchobbies8, TTxBG10, e2bcea, AFfbG10, BGVDay10%off, BGAFF10OFF, bGhOnEy10, BGdragonBoat, BGSS10%SW, BGRC902, BgoFErTaSchInA10, Parts8, BgcLuBofErtA10, BGDAVIS, BGHONEY2110, BGRCParts8, BG1efeb0, 8Couponsde, MVC8SPRING, BG8RCToy, Cuponation9, 9OFFSUMMER, BGMatt2022, BGToys8, BG589b2e
(probably won’t work, but you can try them out)
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
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 5x JST Connector Plug RC is here. The lowest price was: $2.12.
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)).