I have just checked coupons. The lowest price I could get is 39.99 USD for RX-009 Professional (in Banggood). Check coupons or create price alert down below. Let’s see what best price is ATM.
Latest coupon and price update (UTC):
Banggood (39.99 USD)
Banggood warehouse is located in China. I’m afraid that there’s no working coupon in Banggood. Good or bad price? Current price is the lowest in history (according to CouponsFromChina database)!
Link: Banggood product page
Price: 39.99 USD
39.99 USD – This is the best price ever noted in my database!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGWDT15, BG76cfa1
(there’s a little possibility that old coupon will work)
Aliexpress
Click here… to search for RX-009 Professional Knife Sharpener with 4 Whetstones on Aliexpress
Here are coupons that you can use.
Price history and price alert
Check out price history chart (for all/most countries) for RX-009 Professional Knife Sharpener with 4 Whetstones.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).