Brian Way recently reviewed an impressive new wall scanner from DeWalt, the DCT419. Its chief virtue, besides working well, is that it sells for about $400. In the wall scanner category $400 would be considered inexpensive.
But what about folks who have nowhere near that kind of money to spend, need to locate studs, and aren’t worried about finding pipes, wires, and ductwork? The midrange solution would be a $10-50 stud sensor—which takes batteries and has something of a learning curve. Down from there would be the old-school stud finder, a tool that uses a magnet to find the fasteners holding lath or drywall to studs. The studpop is one of the better magnetic stud finders I’ve seen; it costs very little ($10) and is dead simple to operate. Oh yeah, and it's made in the U.S.A. Check it out.