I expect that self-driving cars will -at least initially- be expensive -in large part- because the sensing and computational hardware on the car is expensive.
When the automobile was first invented it would have seemed implausible for it to be accessible and (relatively) affordable to everyone. Look at where we are now.
Yes, but there is an expected near-to-medium-term price floor on the sorts of good sensing equipment that such cars will require, not to mention certified (and patent-encumbered) software to fuse that data and turn it into useful and safe action.
This is stuff that you don't want to cheap out on; it's how the car sees and operates safely!