Unless you can afford to spend money lavishly, I wouldn't even consider a total panel repaint on a daily driver unless it got to the point where the chips outnumbered the painted areas by a factor of 2...
I say this because one of the hazards of driving your MB is that "chips happen", especially with the newer MBs that were sprayed with water-based paints and are less resistant to chipping than the earlier polymers.
You can bet that as soon as you drive out of the body shop with a fresh coat of paint, another pebble with your name on it will ricochet across your hood within a week!
Save the repaint for massive paint wear or actual body damage...spot painting is much more economical for treating the inevitable chips that will grace your MB over the course of your ownership.
There are body shops that do offer spot painting services...I used one when I lived in KC. My daughter (then 1 1/2) decided to use the passenger door on my then-show-competition VW as a drum head...using the business end of a screwdriver as the drumstick! The shop touched up the 20+ nicks for $35...and you could barely tell they were even there!
Try "touch-up" or "spot-painting" as a lookup when you peruse the auto body facilities in your directory.