RF power: +22DBM, Operating frequency: 2.4G ISM band, Software Compatibility: Suitable for radios using OpenTX or er9x/ersky9x, Item name: JP4IN1 transmitter module, Working current: <=100ma, Module bay compatibility: FRSky, Jr and other dimensions: 64*49*33 (without antenna), Working voltage: 6-9v, 20K RAM), Net Weight: 42g (including antenna), Main control chip: STM32F103CBT6 (128K ROM. Basically copy coupon, view price history or create e-mail price alert. What is 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 coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. There is one coupon right now! Check this out.
Link: Banggood product page
1. ($57.37): Parts8
apply it 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): BGaDmITAd, BGCITYADS2019, BGMD10, BGJPN30, 2020CNY, BGVDay10%off, bGhOnEy10, bgshOOp10, BGRC902, BGRCRR9, 7d18f7, BGCuponation10, BGDAVIS
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Price history (for all/most countries) for Jumper JP4IN1 RC Transmitter Module is here. The lowest price was: $30.99.
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)).