This project uses RaspberryPi and the Pi camera in a cloud robotics architecture (most processing is done on a laptop over WiFi) and is based on the ForumulaPi code and OpenCV. It costs less than $100 and can perform the full Udacity Self Driving Car challenge (thanks to offboarding most processing to the laptop). Full instructions are here.
It's the entry-level design for our DIY Robcars hack/race series, which is a monthly series in Oakland. Next event is Feb 11 for a build day, and then the full race on Feb 18.