Green Laser Pointer

After having seen a couple in action at some recent star parties, I am
interested in purchasing one of these - they seem ideal for pointing
directly at stars and planets to help people locate objects. However, I
am at a loss as to what I am looking for in one - a quick perusal of
ebay shows models from 5mW up to 100mW. Obviously the more powerful one
is, they brighter the beam, and the further it will travel, but I dont
want to go overboard - they seem to increase in price quite rapidly, as
well as being more dangerous!


Can anyone help advise me on this?