How Much Will The New iPhone 3G BILL Cost?

Ok, so I own a iPhone right now, the original. And I am 100% getting the new one. But what will happen to the bill? I am paying 20$ a month for my data plan and then a dditional 10$ because I am on a family plan. So can anyone tell me how my plan will work out? Will they only add on another 10$ because of GPS, because I heard that the new bill for the new iPhone 3G starts at 30$. And what about 2-year contract? I got my iPhone for Christmas. And I signed a 2 year plan. Will I have to sign another one [making me be signed up for a FOUR year plan?!?!]? Please any information would be helpful. And dont tell me the cost of the iPhone 3G cause I already know that. Lol, so just tell you that because I am sure people will right it. I mean if you want to write it … write it. But I already know it starts at $199. :] Thanks.