> Today a hobbyist can just buy an 1D LIDAR for 150-200$ or a 2D LIDAR for 450$ on seeedstudio.
If yer not picky, you can generally pick up a cheap "repair part" or "surplus" Neato 2D Lidar unit from ebay, for about $100.00 or so. They are generally pulled from broken Neato vacuum robots. Alternatively, a used Neato (or sometimes even a new one) can generally be had for under $450.00 (plus you get a ton of other robot experimenting parts!).
Another option for hobbyists are used SICK serial-port lidars; I've picked those up for around $300.00 off ebay. They run on 12-24 volts (great for vehicles and electric wheelchair-based platforms), and use RS-232 or RS-422 for communications (where it becomes a PITA is when they are set to the RS-422 protocol - because then you need a special adaptor - and not all of the adaptors work - to reprogram it - using a piece of software that runs on Windows NT4).
They are very robust units, though. Big, and heavy (not for small robots - not at all; these units are about the size of a coffee maker). There are three main types - each with a different color case (yellow, blue, and grey). One of them is an "area coverage" only sensor (and doesn't have a way to output scan data), while the other two are more generalized (at least, this is what I recall - I probably have some details mixed up).
These are on the used market because companies are phasing them out, I believe, for the newer ethernet based models.