I have nearly a dozen Red Dot sights on various pistols and revolvers. I like them really well and they have given me back my "good targets".
They do eat batteries if you forget and leave them on. I was really turned off when I saw what various dealers were charging for the batteries. That is, until I found:
http://www.batterybob.com/category.asp?cat=9024
Battery Bob offers free shipping and heavily discounted prices on name brand batteries. I have been using him for many different batteries for various electronic devices. He is extremely prompt, also.
FWIW
Dale53