Mifi/Personal mobile hotspot thingy?

I'm going to Europe this summer like I do every year, I'm 16 and my uncle absolutely hates the thought of anyone using the Internet like completely. If you ask him to use the computer he will flip out. If you ask him for the Wi-Fi password he will flip out. So I was wondering, I wanted to get the mifi thing -AT&T unite- in white. On the AT&T website it says.99 cents (with a two year contract) I just want to know how much the two year contract part of it will cost. Because I'm going to use the mifi for my iPhone 4S and ill be gone for two months so how much would it cost for two months? And also if my phone is tmobile would I have to switch my plan to AT&T to use the AT&T unite mobile hotspot? I just would like to know the pricing of everything please. I want to have a nice summer with Internet and beaches and everything. My uncle is just too stubborn. Oh! And if it helps with the pricing too, the country I'm going to is Montenegro.

You can't sign a contract unless you are 18 you have to get your uncle to sign it for you or someone 18+ and its only.99 cents for people with really good credit, if you do get the mifi though and you take it to Europe it will roam onto a European carrier and you will get a huge bill when you come back for data roaming I believe data roaming internationally is like $15/MB