I use a "Goodyear" branded 24 volt that I got at Pep boys a few years back, day after thanksgiving sale. The battery crapped out, but I'm using an 18v Ryobi battery in it, and it's great for the $70 I paid.

There was an article (or forum post) I read online where someone compared the Goodyear to a much more expensive gun, and while the more expensive one put out more torque, it wasn't a blowout if my memory serves.

All I know is I'm happy with mine.. but I never use it for torquing-in parts, just removing them.