As for straight body lines and outlining features you can get tape that outlines the width you need, (like used in body shops to redo factory pin striping) and paint them yourself. This is fairly easy and only takes a sraight eye... I've done many factory stripe jobs when I worked in the body shop.
As for custom designs you could go to some car shows and if there is a pin-striper there you could have them do it, usually reasonably priced.
Or,
If you have time to practice and feel like purchasing a stripe kit, I would go for it yourself.
Just a few options, hope they help.
~j
