Aliexpress
Click here… to search for Pet Dog Raincoat on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (14.55 USD): Cuponation9
Coupon (15.03 USD): BG00c906
(CouponsFromChina.com tip: coupon code has to be applied in shop’s cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGGDYYJP, bGhOnEy10, BGXYYGGJP, BGJJCWJP, bgshOOp10, BGHome15%, BgcLuBofErtA10, BGNOTD913, BGAFF10OFF, BGCuponation10, 13f142, BGHONEY2110, BANGGOODSD, 00c906, ADMITAD2212, 2022ACTIESNL, Terence, Tabby20, 2203ActiesNL, BG1efeb0, 8Couponsde, MVC8SPRING, 8BGwbg2204, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN, BGJUNEGSG9
(these coupons are old, so probably won’t work)
Price history and price alert
Check out price history chart (for all/most countries) for Pet Dog Raincoat.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).