Neato Robotics has developed a planar scanner that costs $30 to build--It's on their robot vacuum. See "A low-cost laser distance sensor", http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4543666...
"The video is showing amazing new thingamabobs that will get less expensive over the next few years, and pretty soon you will all be able to use robots like this in your everyday life".
The problem with trying to make money using robots is that we still have plenty of people on the planet looking for unskilled work. I don't think we will reach the economies of scale necessary to make robots practical unless that changes.
This reminds me of: "I’ve long been interested in Navicubes, which is what I call a small and not-quite-here yet $5 box that always knows where it is, which direction it is facing, and which way is up. Besides vehicle nav, intelligent toys, and robotics, these would open up all sorts of neat tricks, such as a ball you could simply bounce off cave walls for mapping."
http://tinaja.com/glib/funstuff.pdf (Don Lancaster)(The Blatant Opportunist #72)(2002-NOV)