Modulations: PXX or CPPM (auto-detected), Upgrade Interface: Smart Port, Compatibility: R9 series, Vin Voltage Range: 4V-12.6V, External Power Supply: 4V~12V (2s Li-Battery is recommended), Telemetry Interface: Smart Port, or it will damage), (*3s Li-Battery is not recommended as external power supply.
You can create price alert here, copy coupons and view price 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 coupon code price check (UTC time):
Banggood
Banggood warehouse is located in Hong Kong. I found coupon for you. Check this out.
Link: Banggood product page
1. ($77.39): TTxBG10
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): 10R9M, 502C6B
(these coupons are old, so probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for FrSky R9M 900MHz RC Transmitter Module. The lowest price was: $73.09.
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)).