The American system is for the standard GSM on 1900. Most companies offer deals to buy a cell phone for a penny or for free, but they almost always come with a one-to-three year obligation and a monthly bill that may not be in your best interest.
Expect to pay around $40-80 a month depending on your plan and how much time you spend on the phone. "Texting", or sending typed messages is becoming increasing popular and is almost always included in a plan, but check how many minutes are available a month on your plan because overages are expensive. It is important to understand all the details of the contract before signing.
Prepaid phones can also be purchased for a small price and then you must purchase minutes.
Some of the most popular companies are Sprint, Cingular and Verizon.