Battery: Built-in 380mAh Lithium battery, Bluetooth version: V3.0, Operating range: 6-8 meters, Working time: About 20 hours.
You can create price alert here, copy coupons and view price history. Best price?
Aliexpress
I could not find it 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. ($30.99): elec
2. ($30.99): AFfbG10
just apply this code in your 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): e2bcea
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Here is price history (for all/most countries) for iPega PG-9023 Stretch Gamepad. The lowest price was: $19.11.
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)).