Teensy USB Development Board
From Wildsong
I have a Teensy 3.2 USB Developmnent Board from PJRC, along with the audio adapter for it.
I have yet to fire it up. Sigh. Got it a year ago (May 2016).
The intention was to build a device to record NFS (noctural flight calls) of migrating birds.
It uses an ARM Cortex M4 processor and it costs < $20. The audio adapter has a slot for a MicroSD card on it.