Red or green laser?

Question on which laser to buy. I've seen red lasers used to check on the surface of a mirror that was being ground. If I'm correct it was to see if the beam would reflect back, rather than penetrate, indicating more work needed to be done. But I see that green lasers are
used when pointing out objects in the night sky. My guess is, a 5mw or less power red laser would serve just fine when it comes to working on a mirror. Is this enough for pointing out object in the sky? Or does one need a green laser to do this? I realize atmospheric
conditions will affect how well a laser works outside but under normal conditions is more than 5mw needed here? I've checked out some web sites posted on this NG which sell lasers. But many that I've checked are selling high priced items. If a $50 green laser does the
job, why spend $200? True higher power may come into play but it seems some sites are simply counting on curiosity caused by newspaper articles to sell overpriced lasers. All I need is a simple, laser for the night sky with a dead man's switch to prevent accidnets from
happening, any suggestions? I can buy a red laser anywhere it seems for as little as $9.99 to about $59 at some stores including radio shack. Again, 5mw on a red laser seems adequate for mirror grinding, why waste money but for night sky use is a green laser required?
Thanks in advance for the help!