A $35 tool like the following will do the trick
Bennett,
That works well if you can already see the wire, i.e. you can touch the wire with the device. It is great for picking a hot wire out of a bundle of dead ones. It won't work well for a wire buried 6 to 12 inches deep in dirt.
Matt, I have a tool that will sense a wire a couple of feet deep, but it cost about $220. Call an electrician. If you destroy the wire in the process of finding it, you aren't saving any money!
Stretch