Cell phone carriers make us pay extra for internet connection?

Yes, l know cell phone without internet connection is incomplete. I had a smart phone with AT&T network having best internet connectivity but for that I had taken separate data plan for the usage of internet. In that plan I was facilitated with 2 GB free data usage and beyond that $ 10 per 4GB.This plan charged me $ 30 per month. This is with all carriers that they charge extra when u have some pda or other smartphone.I think it will be best that u have AT&T for the best speed on your phone this have a good network service too. And this is near to your allowed budget too, so u will not have any problem with this