[smarx007]

Well, I would like to note that people on a budget have been buying Arduino Nano with USB for $2 from eBay for a long time.

[Mchl]

Or a clone of SparkFun's ProMicro, which is absolutely awesome. It's basically Arduino Leonardo (Mega32U4) in the 'micro' form factor and able to work either on 3.3V or 5V. You can get it at around $3