If you're interested in a quad loaded with open source software right out of the box, take a look at the Sky Viper v2450 GPS. It runs about $150.<p>It runs full ardupilot code, has a ublox gps chip, a taoglas gps antenna, and the video board and transmitter software is open source.<p>It runs a tiny webserver that allows you to configure any of the ardupilot variables, and is compatible with most of the ardupilot ground control software.<p><a href="http://sky-viper.com/product/info/V2450GPS-sd" rel="nofollow">http://sky-viper.com/product/info/V2450GPS-sd</a><p><a href="http://ardupilot.org/" rel="nofollow">http://ardupilot.org/</a><p><a href="https://github.com/SkyRocketToys" rel="nofollow">https://github.com/SkyRocketToys</a>