When I was updating this page, then coupon price was 39.99 USD for MD5090 Underground Metal Detector (in Banggood). Just check coupons out (with price alert and history). Best price?
Latest coupon and price update (UTC):
Banggood (39.99 USD)
Banggood warehouse is located in China. Hmmm… There is no active coupon in Banggood at this moment. Price? Hmmm, price is higher than average (which is 39.49 USD right now), so better set price alert down below…
Link: Banggood product page
Price: 39.99 USD
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BG6f6b98, BGTOOS729
(you can check these old coupons out, but these probably won’t work)
Aliexpress
Click here… to search for MD5090 Underground Metal Detector on Aliexpress
Here are coupons that you can use.
Price history and price alert
Price history (for all/most countries) for MD5090 Underground Metal Detector is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).