Every Pro iPhone has one. So it already got pretty cheap by now. Looking at Mercedes' Level 3 Autopilot tech you can also see how well you can integrate the sensors into the front of a car.
At the time of comment, a LiDAR rig would cost around $10,000. A few years before that, they were more like $100,000. Presumably the cameras are much cheaper.
I would be willing to bet that production efficiencies will be found that will eventually drive that cost down significantly.
