Aliexpress
Click here… to search for YEPO 737A 6/256GB on Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. There is one great coupon!
Link: Banggood product page
Coupon (287.99 USD): BGCITYADS2019
(CouponsFromChina.com tip: apply code in your basket (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): 1B1G1LAP1, 1B1G1YE4PO, 1225CAR
(these coupons are old, so probably won’t work)
Price history and price alert
Check out price history chart (for all/most countries) for YEPO 737A 6/256GB.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).