According to my DB the lowest price is $14.99 for DIY Bluetooth Speaker Kit with FM Radio 87.5-108MHZ (in Banggood). Check coupons or create price alert down below. You probably want to know what is the best price?
Latest coupon and price update (UTC):
DIY bluetooth Speaker Kit with FM Radio 87.5-108MHZ DIY Soldering Project Practice Electronic Kit Solder Assembly Support U Disk TF Card AUX – Full Set
Banggood ($14.99)
Banggood warehouse is located in China. I don’t think there is an active coupon right now – at least in my database. Is it good price? Current price is the lowest in history (according to CouponsFromChina database)!
Link: Banggood product page
Price: $14.99
This is the best price ever noted in my database!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Price history and price alert
Do you need price history chart (for all/most countries) for DIY Bluetooth Speaker Kit with FM Radio 87.5-108MHZ? There we go.
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)).