Dealing with telemarketers, and getting your own back

While reading the thread on likes/ dislikes of the new web site, I read a few comments on telemarketers, and had a thought about hwo to get back at them.

In many countries you can rent a Premium line where people pay a dollar or two per 30 seconds to call your number. Now if you get one of these lines, and ensure that the telemarketers get your number, and, when they call, you take your time talking to them, they’ll be paying you for your time – at a few bucks a minute.

How much do you think you could earn this way?