Different levels of autonomy in vehicles:
Full autonomy: This is what Google has: the car drives itself, and can react to changes and emergency situations. Driver optional.
Restricted full autonomy: Stanfords Audi TTS is fully autonomous, but only in specific situations: it can handle all kinds of roads that it has maps for, but not variables like traffic. Driver optional, but only where applicable.
Emergency full autonomy: Toyota is working on this; the car will aggressively take over from you if it detects an impending accident. Driver optional, but only in emergency situations.
Highway assisted autonomy: Volvo has this system operational in Europe. Passenger cars autonomously follow a truck on a highway in a road train formation. Driver required to lead the train, and in cars for entry and exit.
Highway driver assist: You can buy this system in luxury cars; it includes adaptive cruise control on highways and sometimes lane drift warnings. Driver required to be paying attention.
Emergency driver assist: This system is also available in some luxury cars; if an imminent collision is detected, the car will autonomously apply brakes. Driver required the rest of the time. Its also worth mentioning that anti-lock brakes are a very primitive semi-autonomous emergency driver assist system.
Emergency driver notification: I guess this one may not belong in the list, but here it is anyway: some luxury cars will track driver attention and fatigue and provide notifications if a dangerous situation arises.
Now, about this $150 price… Well, here’s the quote:
It could be only 15 years before self-driving systems become commonplace in cities as the price of installing the systems drops: “At present it costs about £5,000, but we’re working to reduce that to £100,” he said.