Happymodel ES24TX Slim Pro 2.4GHz ExpressLRS ELRS (Banggood, Aliexpress: Maximum receive refresh rate: 500Hz, Frequency Range: 2400 MHz to 2500 MHz, Regulatory Domain: ISM2400, Weight: 50g (without antenna）, RF Output Power: ≤30dBm, Frsky Lite 8pin socket, Brand Name: Happymodel, MCU: ESP32(main) /ESP8285(as ESP backpack), Power supply voltage: 5v~12v, RF chip: SX1280IMLTRT, , Antenna gain: 1.87dBi, Dimension: 67.5mm*30mm*20.5mm (without antenna), Model: ES24TX Slim Pro, Minimum receiver refresh rate: 25Hz, Item Name: ES24TX Slim Pro Micro TX Module (the best price with coupon)).
Basically copy coupon, view price history or create e-mail price alert. Let’s see what best price is ATM.
Aliexpress
There’re some similar (or not) items on Aliexpress
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 China. I found coupon for you. Check this out.
Link: Banggood product page
1. ($57.95): BGMatt2022
apply code in your basket (cart) after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BG92a9c2, Parts8, BGRCParts8, Tabby20, BG1efeb0, MVC8SPRING, 8BGwbg2204, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN, BG8RCToy, hoNEYbGdeAlS, BGRCT10, BGJUNEGSG9, BGRADIORU
(there’s a little possibility that old coupon will work)
Price history and price alert
Check out price history chart (for all/most countries) for Happymodel ES24TX Slim Pro 2.4GHz ExpressLRS ELRS. The lowest price was: $48.99.
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)).