Bob Bonneville wrote:

I have a need to locate my buried Invisible Fence wiring at several
locations prior to digging. I have been considering getting a metal detector
for other reasons, on eBay. Will a metal detector work for locating this
wire? If so, will the cheaper ones do the job?

I have used a portable AM radio successfully. Start near the
transmitter and tune across the band to find the frequency that picks
the buzz up the best. You can then use it like a detector, listening
for the buzz emitted from the wire when the transmitter is on.

Thad