I have checked all old coupons and price is $209.99 for DIDEEP X4000Pro 1L Scuba Diving Tank Snorkel Equipment (in Banggood). Basically copy coupon, view price history or create e-mail price alert. Let’s see what best price is ATM.
DIDEEP X4000Pro 1L Scuba Diving Tank Snorkel Equipment Leisure Outdoor Swimming Spare Oxygen Portable Capacity Use 10-20 Minute with Adapter Diving Goggles Strap Bag Handbag – Black
Latest coupon and price update (UTC):
Banggood ($209.99)
Banggood warehouse is located in China. Too bad there’s no coupon right now in Banggood. I think you want to know if the price is good. Well, this price is higher than average price ($178.62)
Link: Banggood product page
Price: $209.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGBFDAY8, BGSPRING8OFF, BGHONEYSP, BGESJY8
(probably won’t work, but you can try them out)
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Price history and price alert
Here is price history (for all/most countries) for DIDEEP X4000Pro 1L Scuba Diving Tank Snorkel Equipment.
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)).