I repainted a number of frames BITD. Repainting is a major amount of work. Having someone do it will cost $200 to $500, good jobs are at the higher end of the range. Also consider a nice newly painted frame with bad chrome looks - well you figure it out. Same with tatty components.
I had a frame repainted a few years ago - $300 +$50 for decals (extenuating circumstances).
I avoid buying bikes that need repainting. I flipped a few but I picked them up cheap for a friend and sold them for my costs.
On older frames you never know what you're going to find after you strip the paint off. Rust pin holes = tube replacements.
I've seen a few nicely done rattle can jobs done by people who took their time. Most LOOK like rattle can jobs!
I use a dental tool to remove small areas of surface rust in areas where the paint has chipped. After removing light surface rust I use Testors hobby enamel paint to mix up a close match. It will last a long time if you keep the bike in a dry area with low humidity.
You can also find auto touch-up paint at car parts stores.
When touching up, you're just doing a camouflage job, not a concors restoration. The bike just needs to pass the 10 foot test... anyone getting closer...
GET AWAY FROM MY BIKE YOU PERV!! 
Before and after:
verktyg
Chas.