In my case, I decided to use my laptop with my MJ because it would cost considerably less, but how much? The simplest way I found to determine the cost was to buy a little gadget called "Kill A Watt." I paid under $20.00 plus shipping from X-tremegeek.com. Do a search for it to find the your best deal.
Keeping my laptop running costs me less than $0.05 per day (under $1.50 per month) with only MJ running. If I'm using the computer also, it is like the MJ is running free. Now that's pretty good. With a two-year MJ contract about $60.00, but the first month free, monthly cost plus power usage is about $4.10 per month! You can't beat that with a stick!

Sure MJ has a few glitches right now, but for the price, I can afford to wait around and help out if I can. I hope they can port numbers before I have to move it to another service, and shutting off MJ voicemail would be great. Maybe Santa Claus can come about nine months early.