Go down and check coupons out. Remember to check price history if it is available. You probably want to know what is the best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest coupon and price update (UTC):
Applicable temperature: 0-55 ℃, Number of Handles: Hands free, Size: As picture shown, Connection Size: G1/2″, Power supply: dc6V, Surface technology: electroplating polishing, Sensing distance: 33cm ± 18%, Static power consumption: ≤ 0.5w (d.c) ≤ 3w, Material: Copper, Flow Rate: 2 GPM (7.57 L/min), Applicable water pressure: 0.05MPa-0.6MPa, Installation Holes: One Hole, Color: Silver
Banggood
Banggood warehouse is located in China. There are no coupons for this product in Banggood.
Link: Banggood product page
Price: $-3
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
There were country-specific coupon codes published on Couponsfromchina social channels and price alerts. Coupon price may vary by country, because there’re different VAT rates, shipping cost etc. There is a chance that some latest coupons are still working:
Old coupons (from the oldest to the newest): BG30c56c, Cuponation9, BG9cbbf9, BG8ReviTrage, BGcoupon8off, BGGutscheine, BG8OFFCOUPON, TTBLACK5, BG7d7282, BG6e326e, BGSCHOOL8OFF, BGCAPITALOS8, BGCOUPERT8, BG8FORMULAMX, BG124578
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Here is price history (for all/most countries) for Bathroom Sink Sensor Tap.
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)).