I've had an Amprobe "Hawk" AT-3000,for about 10years. It cost around two grand,but when you consider how useful it has been, how many times I've used it and how much money it has made and saved, it was worth it.
I use it for locating underground problems, finding where power is fed from, finding buried junction boxes,etc.
It's also useful for locating existing power to signs and pole lights when we're putting in a new foundation nearby so we don't hit it while digging or drilling and are able to reroute and reuse it.
This tracer has two other modes, one that detects power underground, and another that picks up radio signals in buried conductors. I rarely use those two functions. I mostly use the transmitter and receiver together to trace wires.
When tracing a wire it is also able to give you the depth it is buried with a good deal of accuracy.
A quick Google of that model# indicates that it is discontinued, but some refurbished are available, and a newer model has taken its place.
Ebay might have the original also.
Hope this helps,