My significant other has decided she needs some fairly heavy items hung on
the walls. I'd really like to anchor these into studs if possible, and hate
playing "find a stud" by tapping the wall until the tone changes then
driving a skinny nail to see if my knuckle and ear were properly calibrated.

Anyone got a recommendation for a good stud finder? Cost is a factor here -
this won't be a tool I use that often.

Our walls are sheetrock over wood framing if that helps.

Thanks in advance,

KB