What do you intend to use it for? Telecom/data, residential power (120/240V), commercial/industrial power (480/600V), finding conduits or wires underground or in walls?
I use a couple of Progressive Electronics products; one is a telecomm toner/tracer for tele/data and deenergized power wiring. Cost about $100. The other is a live line tracer set that also will find a line up to two feet underground. Cost about $300.
With any tracer, it takes experience to get good results. And fresh batteries. The signal drops off gradually as the signal generator battery gets weak, and you often don't notice it.