You can pick up a SIM card at any Walmart (everywhere) for .99 cents. http://www.walmart.com/ip/Straight-T...n-Kit/34565627
The variety of prepaid cellular plans is endless, but the Straightalk/Walmart ones are probably the easiest for a visitor. From $15 to $250, pick your poison.
http://www.walmart.com/browse/no-con...&browsein=true