Lot of lasers out there, especially for our glocks. Personally, I want the lasermax internal for my G22, but I'm waiting for them to bring out a green-dot version.
In the meantime, wanted something I could play with, that wouldn't cost a bundle. So poking around on Ebay, I find this company called 'PSL Lasers'. Searched my gun type, and here's this cool looking little rail-mount... for $30! Now I'm a firm believer that you get what you pay for, and I know what quality lasers go for. But for $30, if it's a piece of crap, who cares. So I ordered it.
Outta the box, it was pretty nice. Fit perfectly, and I gotta admit, looks cool as **** on my Glock. Different story at the range though. Sighted it in, fired one shot, and it was now 6' off the mark. Two more shots, and it wasn't even on the paper.
So after it spent the next week providing hours of fun for my cats, I had a thought. I took it to the shop. Pulled the Allen screws, and carefully pried it apart w/ a small flathead. I then filled the chamber that the actual laser sits in with Permetex Ultra-Gray($3 at any auto parts store). Put back together, cleaned off the excess, and sighted it back in. Don't worry, the gray stuff takes awhile to cure.
Waited a day, then back to the range. Happy to report, 400+ rounds down the pipe so far, and it's still dead on the mark. $33 and 10min of work? Not too shabby I'd say.