I'm looking at about $85-ish per month for 450 minutes, 5000 anytime, unlimited mobile to mobile, unlimited data, and unlimited text. It could be a touch more than that, but it's OK - will be worth it. I've already gotten a few more apps... but I'm waiting on money at the moment, so mostly free ones.
Initial thoughts? It's awesome.
I bought a case already as well. Specifically one of the Griffin Elan Form cases - the black leather version. The case itself is OK, but the screen protector it came with SUCKS. I have one of these same cases on my iPod Touch and it's great - and the screen protector is one of the stick on versions. This one for the iPhone is not. It is just a piece of plastic that is held in place by the rest of the case - but it creates a gap between itself and the screen that you can feel and definitely notice. Plus dust and dirt and stuff can get between the protector and the screen around the home button/speaker.
So I still like the case, but ditched the protector in place of a ZAGG Invisible Shield. Just put that on a little bit ago and have to wait a bit for the rest of the water to dry under it. It kind of goes on like window tint - a little water and then the protector, then squeegee. So far so good. The texture is a bit different, but it's OK so far.