HOW MUCH WILL AN IPHONE COST ME IF I JUST WANT A LOWER-END CALLING PLAN AND THE INTERNET?

I frequency speak on the phone but I make make use of of the internet a lot. I wish an iphone for the preference of the internet at my fingertips. How most would I be seeking at per month for a simple job devise and the internet? Also, can I make make use of of the internet anywhere or do I have to be in a prohibited spot?