Let's be fair, adafruit is expensive.

https://www.aliexpress.com/item/1005004551394154.html this is 32eur

+ ~5eur for an esp32 board and some wires

+ http://docs.espgeiger.com/output/webportal

This gives you a measurement node, with mqtt support, online data export and a web interface.

For ~40eur all together, it's still very cheap.