There's a member here that did his own. Can't remember his screen name but his YouTube is Merricks Garage.
The wrap material is permiable so it won't trap moisture. With that in mind, I would question its ability to prevent rust, or the spread of it. It would be best to apply over good paint.
It also won't cover blemishes. The vinyl will adhere down into any dings, dents, or paint chips.
Best deal is if you can apply it yourself. Like ChrisPerry said, if you add install it's going to get up to $2000+. There are tons of YouTube videos that show wrap installs for tips on how to do it.