Many people think that ARM is very hard to use and require 4-6 layer PCB with lots of support circuitry. This proves that you can have it working as simple as plain old AVR - just single layer single sided board, linear regulator (3.3v), capacitors before(optional) and after(2.2-4.7uF ceramic) regulator and single resistor at BOOT0 pin to enable boot from internal flash. That's it, your ARM is working :-) Also, this PCB is homebrew using toner transfer method, no rocket science. Microcontroller is simplest STM32's stm32f100c4t6b - just under 1$.
