Channel: XSR-16CH(1-16CH from SBUS channel, 1-8ch from CPPM Channel), Dimension: 26x 19.2x 5 mm, Weight: 3.8g, Operating Voltage Range: 4.0~10V, Operating Current: 100mA@5V.
Just check coupons out (with price alert and history). Best price?
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.
Link: Banggood product page
1. ($15.46): BGaDmITAd
2. ($15.63): Parts8
put item in your cart and apply coupon code there 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): FRXSR, 20OFFRSF, 502C6B, 10Frsky, BGFrXSR, BGXSR12
(probably won’t work, but you can try them out)
Price history and price alert
Check out price history chart (for all/most countries) for FrSky XSR 2.4GHz 16CH ACCST Receiver. The lowest price was: $12.99.
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)).