Basically copy coupon, view price history or create e-mail price alert. Let’s see what best price is ATM.
250W motor, max 25km/h speed, max 25 degree gradient, 7.8Ah Li-ion battery, 16 inch inflatable rubber tire for different grounds, max 30 – 40km mileage with pure electric mode and 60 – 80km mileage with moped mode, Charge time: 5 hours
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($499.99): BGFDD2CN
2. ($641.00): 7bcdf9
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 and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): issamfiid2, PICODICOM, 5dd9c0, 6d9494, itfiidod2, BGFD201, BGFDD2CN19, BGFDD2CN11, BGFDD2CNB5, bGpAnDacHeCk, 2880c7
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for FIIDO D2 Electric Bike Gray 7.8Ah.
Price records source(s): Gearbest, 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)).