um.. yes? I can't imagine getting an iphone every year when you can just get one every 2 years for a third of the price.
Historically, US carriers don't change plan pricing based on having a contract. So, you can be month-to-month for $100 per month, or get a two year contract for $100/month plus they give you $500 up front towards the purchase of a $1,000 phone (as received by just discounting the phone up front).