Octa Core, CPU Qualcomm Snapdragon 653, Resolution 1440x 2560 pixels FHD+, GPU Adreno 640, ROM 64GB, 4180mAh(Built in Polymer Battery), RAM 4GB, OS Android 7.1.1, Display Size 6.0 Inch Conring Gorilla 4 Glass.
Just check coupons out (with price alert and history). Let’s see what best price is ATM.
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.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. I am tired of searching coupons, but I found one for you…
Link: Banggood product page
1. ($112.99): Email5
coupon code has to be applied in shop’s cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BG5F9
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Check out price history chart (for all/most countries) for YU FLY F9 4/64GB. The lowest price was: $88.99.
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)).