Much more expensive though.

Are they?

$24 for a Teensy 4.0 over at Sparkfun. That seems reasonable to me.

I do miss the older Teensy 3's and 2's.

I should have said "Much more expensive though compared to something like an ESP32 or RPi Pico". You can get something like an ESP32 Wemos D1 Mini on Ali for $4 to $5 USD, and besides solid performance and I/O, you get integrated WiFi and Bluetooth. Not to mention a community that is likely substantially larger than that built up around the Teensy.

ESP32, STM32 or Pico can be found for $2-3.

Depends which model. Arduino Mega retails in Europe for around 50 euro.

Teensy 4.1 is a beast, also quite power efficient.

Was looking for this comment. Long Live Teensy!