I have my phone through Skype. It's under $90 a year: $30 for the phone number per year, and then $54.00 for the 12 months of Skype premium. It runs right through my computer, and I can call whoever I want, whenever I want.
I'd thought of Magic Jack, but this was just more convenient for me since my computer is almost always running.
Also, of course I have internet, which is needed for it too, so I guess that would increase the expense... except that I would have already gotten internet service, so it's really not adding anything anyway.