4 dollars, including shipping. At this price, they're pretty much disposable. Pi's seem to have bad shipping costs, so they're 20$/piece for the cheapest: http

4 dollars, including shipping. At this price, they're pretty much disposable. Pi's seem to have bad shipping costs, so they're 20$/piece for the cheapest: https://www.banggood.com/ATmega328P-Nano-V3-Controller-Board-Compatible-Arduino-p-940937.html?rmmds=search https://www.banggood.com/ATmega328P-Nano-V3-Controller-Board... 14 GPIO (although with hacks you can do more), including 10 bit DACs on all of them, and 4 with hardware PWM. Most have alternate functions, like I2C, that can be used.