I love the Arduino, but the boards are expensive when compared to other platforms. I recently started using the TI MSP430 Launchpad which is $4.50 shipped! It's

I love the Arduino, but the boards are expensive when compared to other platforms. I recently started using the TI MSP430 Launchpad which is $4.50 shipped! It's also very flexible and uses very little power. If you want the simplicity of the Arduino IDE, there's a port of it called Energia. The Raspberry Pi is much more powerful than the Arduino and it's around the same price. I know the RPi isn't an apples-to-apples comparison.