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.
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 code price check (UTC time):
Banggood
Banggood warehouse is located in China. Only one coupon available!
Link: Banggood product page
1. ($57.95): BGMatt2022
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): BG92a9c2, Parts8, BGRCParts8, Tabby20, BG1efeb0, MVC8SPRING, 8BGwbg2204, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN, BG8RCToy, hoNEYbGdeAlS, BGRCT10, BGJUNEGSG9, BGRADIORU
(probably won’t work, but you can try them out)
Price history and price alert
Do you need price history chart (for all/most countries) for Happymodel ES24TX Slim Pro 2.4GHz ExpressLRS ELRS? There we go. 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)).