$12.59 – ZK-MT21 bluetooth 5.0 Subwoofer Amplifier Board 50WX2+100W 2.1 Channel Power Audio Stereo Amplifier Tone Board Bass AMP AUX.
You can get ZK-MT21 Bluetooth 5.0 Subwoofer Amplifier Board for $12.59 using coupon code (in Banggood). Basically copy coupon, view price history or create e-mail price alert. You probably want to know what is the best price?
Latest price update (UTC time):
Banggood ($12.59)
Banggood warehouse is located in China. Too bad there’s no coupon right now in Banggood. Is it cheap? From what I can see this price is higher than average price ($11.57).
Link: Banggood product page
Price: $12.59
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): 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
Here is price history (for all/most countries) for ZK-MT21 Bluetooth 5.0 Subwoofer Amplifier Board. The lowest price was: $10.99.
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)).