The whole point of powder coating is that it is 10x's less likely to chip and no harder to fix if it does. The shock would still need to be removed from the spring to touch up. If you're that far, strip it and recoat. Powder coating is extremely flexible. When I first started powder coating I would take 3" x 3" pieces of aluminum foil and powder coat some in Candy Blue and some in Metalcast Blue. Take a piece of each and wad it into a ball and then unwed it. The painted one will have chips flaking off all over on the first wad. The powder coated one can be wadded and unwadded until the foil fails and powder will still stick to it, and that's on an unblasted surface. On a blasted surface you have less worries about it. I did an extensive test coating springs because everyone said the heat would weaken the spring. I proved the theory wrong. Coating has absolutely no negative effect on the spring. I'll find the test if anyone is interested. To paint, you really want a good primer and a good top coat. Both are going to run $6-$10 a can, that's $12-$20 for an inferior finish, or coat em and be done for $20.
Figure on $20-$30 a spring for coating.
And again I will add that in the rare event you do chip the powder, if you can find a matching color in paint the chip can be touched up with paint.