Aliexpress
Click here… to search for FIIDO D2 Electric Bike Gray 7.8Ah on Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (499.99 USD): BGFDD2CN
Coupon (641.00 USD): 7bcdf9
(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): issamfiid2, PICODICOM, 5dd9c0, 6d9494, itfiidod2, BGFD201, BGFDD2CN19, BGFDD2CN11, BGFDD2CNB5, bGpAnDacHeCk, 2880c7
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Price history (for all/most countries) for FIIDO D2 Electric Bike Gray 7.8Ah is here.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).