My company has been in business since 2002 and has been profitable every year with no debt. I started off consulting while at the same time building a product, getting contacts in the industry and growing the customer base. As our software matured and the revenues grew, I slowly phased out consulting work.
We are a tiny firm (4 employees) but I like it that way and we do okay revenue-wise. Like you I am very debt averse and don't like outside investors (or partners) telling me what to do and diluting my equity. It is a much slower way to grow your company and requires lots of patience (and luck).