Actually if you're a bit handy and have a piece of siding and the right $8 siding removal tool and follow the Youtube video you can DIY. It does become problematic if the siding goes behind a post or under door trim or under window trim. If it's just a piece in the middle it isn't too difficult.
Amazon.com Siding removal tool
How To Replace One Piece Of Vinyl Siding (Mid-Wall) - YouTube