For good or evil, if you subscribe to do-it-yourself type magazines, sooner or later you'll end up getting a packet of post cards for products you may or may not be interested in. Normally I just toss them unopened right into the garbage can but for some reason I opened up the last package and thumbed through them and found the miter saw laser guide from LaserUS. Price was only $9.95 including shipping when I followed the link on the card (www.Wood-Jan.com/Laser), so I ordered one. The price on the website is $24.95. I've got no idea how well it will work or how long it will last but for less than ten bucks, why not give it a shot.
Howz about that - it works! It runs on three little watch batteries and turns itself on automatically. Even came with three spare batteries. If it works for any length of time, well worth the ten bucks.