LaunchPads are available directly from Texas Instruments and their $5 or $10 price includes all costs, even shipping, and usually a few extra microcontroller chips so you can try different configurations. They are from TI and $5 is much less than $25 or $35 to buy an Arduino or Raspberry PI. Working code samples are provided here.
The MSP432P401R LaunchPad enables you to develop high performance applications that benefit from low power operation. It features the MSP432P401R – which includes a 48MHz ARM Cortex M4F.
Microsoft will resurrect the Start button in Windows 8.1. Texas Instruments launched its ARM-powered BeagleBone Black PC: faster hardware, lower power requirements for $45.