$6.20 – Waterproof 35-80L Rucksack Cover Backpack Bag Cover Rain Cover Perfect for Hiking Camping Traveling Cycling Outdoor Acclivities – 2XL.
ATM you can buy Waterproof 80L Rucksack Cover for $6.2 (in Banggood). Basically copy coupon, view price history or create e-mail price alert. What is best price?
Latest coupon code price check (UTC time):
Banggood ($6.20)
Banggood warehouse is located in China. So I have checked for active coupons (all category coupons and old ones), but there was no working coupon in Banggood. What about the price? Pretty sweet, this is the lowest price I have ever noted for this product!
Link: Banggood product page
Price: $6.2
Additional Banggood coupons: first page and second page
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. Here are coupons that you can use.
Price history and price alert
Check out price history chart (for all/most countries) for Waterproof 80L Rucksack Cover. The lowest price was: $6.2.
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)).