I have been looking for a cheap, quick and dirty way to get my XY set and also to check see if I have lost the setting while working with different pieces. This was made up from two laser pointers that I got off of E Bay. As you can see I have taken them apart and wired in switches and batteries to make them easier to handle.
Really easy to use. Since the X carriage always moves in the same plane once I bolted the unit to the side railsand trued it all I have to do is put the beam where I want the axis to be and do an x zero. With the Y axis I focus the beam on a target that I made up and then, without moving the holder, move the carriage so that the beam is on the target.
It appears that I can reliably get within .025.
Here is a link to the photos http://www.cars4tom.com/cars4tom.com/Laser.html