Interestingly, there are already some comparatively cheap LIDAR units on the market.

In the automotive market, ideally you need a 200m+ range (or whatever the stopping distance of your vehicle is) and you need to operate in bright direct sunlight (good luck making an eye-safe laser that doesn't get washed out by the sun) and you need more than one scanning plane (for when the car goes over bumps).

On the other hand, for indoor robotics where a 10m range is enough and there's much less direct sunlight? Your local robotics stockist probably already has something <$400