Of total last resort, if you cant find one in your area, or borrow one. Check this site, and paste this number in model search.
I only say last resort because you have to pay, and wait for them to ship it to you.
Do you know anyone in the phone company? Almost every truck has one! I once saw one in a pawn shop while looking for stolen tools, they only wanted $100 for it. It was obviously stolen from the phone company so I would never buy it. But most other types of tracers will work also. Like some of these. http://www.electrical-contractor.net/the_store/Wire_Tracers.htm?source=google
A stong phone toner and an insulated #12, could work only if not too deep and only in PVC, but you'll look really silly crawling around on your knees, and still not find it.