Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. There is one coupon right now! Check this out.
Link: Banggood product page
Coupon (78.53 USD): BGAlerabatKL
(CouponsFromChina.com tip: you should apply the coupon in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGLP09, PICODICOM, BGLP09Plus, BGLP9, BGLP45, BGLP945, 7d18f7, BGLP9S45, BGLPS9, BGHOMEAPP, bGhOnEy10, BGL9PL, BGTT10, BGLP9PU, bgshOOp10, BGHOMEAPP13, BGCNL9PLS, BGHOMEA13, BGLOAC1, 13f142, BGBuscape01, BG651551, BGBRPL2, BGHOTSHOP15, BG53e9c8
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Price history (for all/most countries) for LP-09 PLUS 40W Bluetooth Soundbar is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).