Just check coupons out (with price alert and history). Let’s see what best price is ATM.
50Hz/150Hz/250Hz/500Hz (2.4GHz), USB port: Type-C, RF output power: , 25Hz/50Hz/100Hz/200Hz (915MHz/868MHz), Frequency bands (Micro RF Module 915MHz/868MHz version): 915MHz FCC/868MHz EU, Input voltage: 5V~12V, Version: 2.4GHz/868MHz/915MHz (500mW)/2.4GHz (1W), Packet refresh rate: , Brand Name: BETAFPV, Item Name: ELRS Micro TX Module, XT30 port: 5V~12V / recommend 2S(8.4V) battery / DO NOT support 3S(12.6V) or above, 25mW/50mW/100mW/250mW/500mW (2.4GHz), Weight: 125g, Frequency bands (Micro RF Module 2.4G version): 2.4GHz ISM, 100mW/250mW/500mW (915MHz/868MHz)
Aliexpress
There’re some similar (or not) items on Aliexpress
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. I can’t find any active coupons for this product in Banggood.
Link: Banggood product page
Price: $-3
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGRCParts8, Tabby20, BG1efeb0, 8Couponsde, 8BGwbg2204, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN, BG8RCToy, hoNEYbGdeAlS, BGToys1, BGRCT10, BGJUNEGSG9, DealBGimpact, BGRADIORU
(probably won’t work, but you can try them out)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – BETAFPV ExpressLRS ELRS OLED RC Micro TX Module [EU] ($-3)
Price history and price alert
Here is price history (for all/most countries) for BETAFPV ExpressLRS ELRS OLED RC Micro TX Module.
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)).