I don't build as a career, but many people who come to this board have aspirations of building full-time. Let me just tell you what I've seen and know. The custom guitar/bass market is VERY COMPETITIVE. For this reason, unless you are very well known(and often unless you have cheap labor or cnc assistance), you will not make a huge profit margin. It may take you years to just earn enough to pay your general bills, much less live well. Generally, it's accepted that if you don't know how much to sell your guitars for, you shouldn't be selling them. This stems from the idea that when you're ready to sell, you'll have an idea of how much you want to earn hourly, how much parts and wood will generally cost you, and how much time you'll have to invest in any given instrument. Some builders sell guitars after they've built only one or two, some people wait to sell until they've built 10 or 20. However, a general rule of thumb is that the more s*** you send out your door in the form of guitars, the more s*** you'll have coming in your door in the form of angry customers. So DO NOT sell anything that you feel even remotely dissatisfied with. If you want the opinions of guitarists about your builds, let them play them, not just look at them on forums. More importantly, to get honest opinions from them, don't only ask them what they like about your builds, ask them what they don't like or would change about your guitars. This could potentially reveal some flaws in your builds that you had not previously seen or given attention to.
While there are tons of custom solid body builders. It seems that there is a greater demand for custom acoustic or custom archtop builders, or at least that trade is more profitable(I could be wrong, but I seem to remember hearing this on a few occasions). The problem here is that the quality of your instruments tone will rely much more heavily on your building quality and style than a solid body wood. This means that it may be harder to sell your instruments until you get a buzz going about how good your instruments sound. Of course, the opposite holds true for your instruments if they're built poorly and sound terrible.
I'm sure I've missed some things, and remember that this is just what I've gleaned and think. So take it with a grain of salt, but do give these things some consideration.
peace,
russ