I have just checked coupons. The lowest price I could get is 36.79 USD for Blheli_S BB2 2-4S (in Banggood). You can create price alert here, copy coupons and view price history. What is the best price?
Latest coupon and price update (UTC):
Banggood (36.79 USD)
Banggood warehouse is located in China. Coupons for Hakrc 20x20mm 15A Blheli_S BB2 2-4S ESC? Nope, there’re no coupons in Banggood. Is it a reasonable price for this item? Hmmm, price is higher than average (which is 14.86 USD right now), so better set price alert down below…
Link: Banggood product page
Price: 36.79 USD
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): 502C6B, TTxBG10, AFfbG10, BG12MRP, BGVDay10%off, BGAutos, FBCOUPON1, BGAFF10OFF, BGCuponation10, BGDAVIS, BGHONEY2110, Parts8, BGRACING1125, BGGAL8, BGJON8, BGRCParts8, Tabby20, BG1efeb0, 8Couponsde
(I don’t think these’re gonna work, but you can try ’em out anyway)
Aliexpress
Click here… to search for Hakrc 20x20mm 15A Blheli_S BB2 2-4S ESC on Aliexpress
Here are coupons that you can use.
Price history and price alert
Check out price history chart (for all/most countries) for Hakrc 20x20mm 15A Blheli_S BB2 2-4S ESC.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).