"I'm not a member of a guild (I tend not to be a "joiner") and have no real feel for how much demand there is in this area, either."
I think this may be an issue if you are thinking about starting a business. You have to get your name out there, no matter what type of business you start. Referrals go a long way to creating a buzz about your business.
You need to do market research, how many quilters in your area? How many send out their quilts to be quilted? Who is your competition, not just locally but by mail? Do you have any awards for the quilting you have done to date? What is the average rate charged in your area?
You can get a business rider for your insurance, but there are other factors to consider. Do you want people coming to your home? Is there adequate parking? Are there stairs to get to your quilting area? Do you have an exterior entrance to your quilting space? Do your local bylaws allow for a home based business? In Canada, running a business out of your home allows you to deduct certain expenses against your business income, but it can also impact your Principal Residence exemption.
I bought a second hand LA machine because I wanted one for me. I do not quilt for others. I have no interest in doing so. I do not have to justify the cost to anyone.
It ticks me off that nobody bats and eye, when a man buys a boat and fishing gear, or hunting gear, or woodworking tools, an old car to work on etc., yet, women have to justify a major purchase.