I started by advertising on Craigslist services offered section.
Initial start up costs: 0
First job at $10/hr (+$1/mile + expenses), 2nd at $15, after the first week at $20.
My only eventual start up cost (done after a couple months of working) was registering a fictions business name.
I never bought a tool that wasn't paid for fully by the job I was buying it for until 2 years in, at which point I also first invested in a domain name and server space ($25/year), as well as signs for my truck.
I taught myself enough html that I could make my own website instead of paying someone (
biodieselhauling.org)
Soon after that I applied for and received green business certification.
With that, and a few years experience, raised rates to $30/hr
By 4 years I stopped putting up ads on CL, because I got as much work as I wanted from repeats and referrals.
Raised to $40/hr + $1/mile, but with a discount for anyone who doesn't own a car and sliding scale for low-income.
This was more to reduce hours than to increase income, because I was working 30-40 hrs a week, which is just ridiculous.
It has been 5.5 years now. In honor of Maximum Mustache March I started putting up CL ads again, as well as rode around the city (and nearby cities) on my bicycle with 10 poster ads with the little tear off tabs and put them up in locations where my target clients are likely to be, and worked 12 days straight (I normally work closer to 5-15 hours a week, over 3 or 4 days)
Given what you are wanting to do, I imagine you could use the same model. No reason MMM principals shouldn't apply just as much to business as to personal life.