The prices are pretty well set on their webpage. I would call the number or visit a local store, as they can put all the information right in front of you, in plain black and white. As far as "waiting" for the lines to run out, they pay your early termination fees, if you decide to go that route.
But before you do anything, make sure that t-mobile works in all the areas that you need it to. While there is no doubt that t-mobile has been increasing their coverage at a very rapid rate, there are areas that verizon still destroys them. For those that live in areas that t-mobile covers, it's all very good, but if you're NOT in an area that has coverage, it can be rather frustrating.