I have used them in a Glock 22, 23, also in a 32, 357 Sig variant. They're fairly accurate, but there is one problem that I've noticed. They tend to turn themselves on/off with the recoil of the weapon. They're definitely a fun toy to play with at the range, but I've removed them from both of the guns they were installed in, just use a good pair of night sights instead.
I've heard nothing but good things about them, although they shouldn't be used as a substitute for your pistol's sights. I've never used one myself, though.
One thing that you should be careful of: I recently took a Glock Armorers course, the slide stop lever (which is replaced with the lasermax to be used as the on switch for the laser) can be easily installed incorrectly. If it isn't correctly installed, your first shot will be followed down range by the slide. Have a Glock Certified armorer do the work for you. If the slide is damaged, I doubt that Glock will replace it under warranty.
There's an article about the lasermax being installed & used in a G22 in the November '04 issue of Guns & Weapons for Law Enforcement. I believe it's still on newsstands now.
It depends on the model of gun but ...MSRP is like $329 on average,
LE price direct is something like $289 or so...you can call and aske them based on a specific model but I think those prices hold true for most glocks.