public frequency band, Battery 18650 lithium ion battery, Input 5V, Charging temperature 0-45℃, Modulation method 16K0F3E, Working temperature -20-50℃, Interface type USB, 8K50F3E, 0.5W, Frequency band U segment, Radiation ≤7.5μW, Transmitting power 3W, 409.7500-409.9875MHz, 1A, Battery capacity 2000mAh (7.4Wh), Model AMDJJL01, Receiving sensitivity -122dBm (12dB SINAD), Frequency range 430MHz-440MHz.
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.
Updated:
Banggood
Warehouse in China.
Link: Xiaomi Lite Walkie Talkie 2000mAh AMDJJL01
$53.00 with coupon: Tabby20
$54.77 with coupon: Terence
$55.36 with coupon: BG00c906
Additional Banggood coupons:
1. First page
2. Second page
Price history and price alert
Price history (for all/most countries) for Xiaomi Lite Walkie Talkie 2000mAh AMDJJL01 is here. The lowest price was: $17.99.
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)).