ATM you can buy USB Cordless Rotary Tool Kit for $9.99 (in Banggood). Basically copy coupon, view price history or create e-mail price alert. Let’s see what best price is ATM.
Voltage: 3.7V, Speed: 10000-15000-20000rpm, Battery capacity: 380MAH, Clamp Depth: 25mm, Charge input voltage: 5V 2A, Power: 10W, Attachment: 2.35mm
Latest coupon and price update (UTC):
Banggood ($9.99)
Banggood warehouse is located in China. I couldn’t find any coupon for this product on latest product update. Low/high price? Pretty sweet, this is the lowest price I have ever noted for this product!
Link: Banggood product page
Price: $9.99
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 USB Cordless Rotary Tool Kit? 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)).