The previous HDL-64E model was about $75k when it was first released; I don't know if there have been significant price drops since then.

I'm guessing the steep price was mostly caused by the need to recoup R&D from a small volume of sales, rather than the cost of actually manufacturing the sensors.

> How many of these does one need in a self-driving car?

I think that definitely depends on the company you talk to. Tesla right now says 0. Other companies have been seen with 1-5.