I used to rent a Gammill, and I loved it. The cost was based on the hours you used the machine. Most quilts that I did cost about $40.00. I loved it, but all I was able to do were pantos. Sadly the shop went out of business and she sold her longarm machines. It was fun, but doing it for others would be too much like work, and if I wanted a job, I would still be working not retired. I think quilting for others would be difficult, many "customers" are very picky when money is involved, although quilters are probably the best to work for. Good luck with your endeavor. The shop owner told me that her machines were hard to get serviced, but I found out that there are no dealers in Michigan, so maybe that was the problem. Good luck with your endeavor.
Sue