This question is best answered by how complicated the surfaces are, and how much hardware there is that has to be either removed or painted around. Flybridge boats, for example, are particularly costly to paint due to all the convoluted surfaces and tight quarters where it it very difficult to both prepare and spray these areas. Express cruisers without superstructures and open boat make the best candidates for reasonable cost paint jobs. Check around as to whether there are any painting specialists in your area. In places like South Florida, there are dozens of them where competition keeps prices reasonable.
Trailerable boats make excellent prospects for repainting due to their portability and small size.
Plus you may be able to find brush-on specialists that don't require the added cost of a spray booth. My answer to that is that brushing is just fine for smaller boats, say in the 30 foot and under range. There are contractors out there who can lay Awlgrip on so well that you'd have a hard time telling that it was brush painted. This is less true for larger boats with larger surface areas. As boats get older and go through one owner after another, the electrical systems tend to get so jury-rigged with substandard wiring and additions that the basic electrical system is no longer reliable.