$13.99 – Material: ABS, , Output Voltage: 3.7V / 10A, Color: Gray/Green/Red, Idling Time: 2 hours, Package Weight: Approx. 183g, Input Voltage: DC 5V USB, Polishing Working Time: Up to 1 hours, Choose：Standard Model / Deluxe Model （optional）, Collet Chuck Diameter: 0.5-3.2mm, Rated Power Input: 10W, No-load Speed: 5000/10000/15000 r/min.
According to my DB the lowest price is $13.99 for USB Charging 10W Grinding Machine (in Banggood). Go down and check coupons out. Remember to check price history if it is available. Do you want to know what the best price is?
Latest coupon code price check (UTC time):
Banggood ($13.99)
Banggood warehouse is located in China. Too bad there’s no coupon right now in Banggood. Well, is it a good price anyway? This price is higher than average price ($13.32) for this item.
Link: Banggood product page
Price: $13.99
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BG589b2e, BGPT07
(I don’t think these’re gonna work, but you can try ’em out anyway)
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
Do you need price history chart (for all/most countries) for USB Charging 10W Grinding Machine? There we go. The lowest price was: $12.99.
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)).