I have just checked coupons. The lowest price I could get is 6.69 USD for W520 2.4G (in Banggood). Basically copy coupon, view price history or create e-mail price alert. Do you want to know what the best price is?
Latest coupon and price update (UTC):
Banggood (6.69 USD)
Banggood warehouse is located in China. There is no active coupon in my database right now (for Banggood). I think you want to know if the price is good. From what I can see this price is higher than average price (6.66 USD).
Link: Banggood product page
Price: 6.69 USD
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BG589b2e
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Aliexpress
Click here… to search for K-Snake W520 2.4G Wireless Mouse on Aliexpress
Here are coupons that you can use.
Price history and price alert
Do you need price history chart (for all/most countries) for K-Snake W520 2.4G Wireless Mouse? There we go.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).