Do you have to get internet on BlackBerrys?

Okay so I have been having problems with my Gravity 2. I have had them send me three of them so they are sending me a new Gravity 2 and they are giving me a free upgrade. I want to get a Blackberry Curve 8520 fuchsia red. I was wondering if I have to get the internet with it? If I have to get the internet how much will it cost?