How much will i have to pay for the iphone 3gs?

My family has been with at&t for awhile now and we've always got the regular phones.. nothing special.. until about a year and a half ago i got the blackjack 2. Recently i've decided i want to get the iphone 3gs.. will i still be eligible for the $199 price advertised? or because i have a smartphone already would i have to change something and make it cost more?