Serious Linux nerds are in high demand and low availability almost everywhere I've ever lived. But, if you're not well-equipped for IT, that might not be the way to go. Tech support is also the highest stress technical career (there was a study about it a couple of years ago, and if I weren't lazy I'd look it up), so you don't want to do it for long if you haven't the patience of Job. But billing $100/hour is not at all difficult, so you only have to work three or four days a month to scrape by...don't underestimate the time spent on paperwork and such, though...some companies make you work an extra day for every couple of days you work, in dealing with expense forms and other assorted crap. I much preferred working for small companies, where one person made the decisions and when he or she said to the accountant, "Write Joe a check", it would be in my hand before I walked out the door.
But, IT has the advantage that you're generally working on small jobs--things that can be fixed in a few days, or a couple of weeks, tops. They are well-defined, like, "We need to move our web servers to a new data center", or "our mail server isn't filtering spam and it's letting viruses through". You know when you're done with this kind of project, generally.
That said, startups are kinda like a marriage. Having a little something on the side isn't likely to turn out good for the startup. Have you considered raising a little money to get you to launch and revenues?