New tiny beaglebone

Electronics
1

And it is currently available from Mouser for $25

http://www.mouser.com/ProductDetail/BeagleBoard/PocketBeagle-SC-569/?qs=%2Fha2pyFadujarMkBbJ8XRQvjRGpau8wIeIJ8IYIwmPaeBvB5K%2bjrC0XGT5XSSjvV

The big advantage the beagle platform has over the Raspberry Pi, are the PRU units, which allow realtime response, even under standard Linux. They are co processing units.