try your local stores or even try craigs list, they post this kind of services a lot, i tried doing it my self on an iphone 3gs and after a while the touch screen corners wouldnt work. i was lucky they didnt realize it on the apple store and i was under warranty.
you can buy the screen for cheap pn amazon just make sure to read the reviews. Many are cheap and have discoloration but some are pretty good. there are planty of videos on how to do it on youtube.
Just got finished doing one bro, bought the iphone for $50, paid $59.99 for the blue front/back combo and $12 for the brushed silver metal, works perfect.
