Serious question, is that $40 cable toner from the hardware store ever worth it?
I bought one for a job in a pre-wired apartment building and it gave me a false positive on a dead line, costing me two hours of rework and a frustrated customer.
Yeah, that false positive thing is rough... I've been burned by cheap toners too. I keep a basic continuity tester in my bag now as a backup check. It's slower but it never lies about a dead line.