I've read all the comments so far...I think it's easier and cheaper than people are telling you. I had to replace my dockport on my 3GS. This was a much more difficult repair because I had to take EVERYTHING apart...like, the logic board and all. Your repair will literally be just taking out 2 screws, suction-cupping the screen off...a few ribbons disconnected and the new one on.
This is the repair kit I used...a whopping 2 dollars. http://www.amazon.com/gp/product/B001O2T43M