ArduPilot – Arduino compatible UAV controller. You’ll need a GPS module ($60) and, for all but the most stable planes, a commercial stabilization unit ($70), but still the least expensive autopilot. it’s also a 100% Open source hardware project, schematics and Eagle files on the site. This sold out in 7 minutes today, but don’t worry, backorders are fine as per Chris. Sparkfun is making another hundred, which should be available later this week. Then more next week to keep up with demand…

This is a Arduino-compatible autopilot board designed by Chris Anderson and Jordi Munoz of DIY Drones. This is a basic navigation-only autopilot that requires a GPS module and separate stabilization unit such as a FMA Co-Pilot to create a functioning Unmanned Aerial Vehicle (UAV). The hardware and software is all open source. The board comes with all the surface-mount parts already soldered, but requires the user to solder on connectors. Firmware is already loaded, but the autopilot software must be downloaded and loaded onto the board by the user. It can be programmed with the Arduino IDE. All details and instructions can be found at the project’s home page.