Eventually, I will have my own machine, but for now, I still have someone else do the quilting. There is a LQS about an hour away from where I live that does what you are thinking of. She only has one machine and only rents in 4-hour increments, but she has several zipper systems so that your quilt can be removed when your time limit is up. She also sells the fabric, notions, and the zipper systems in her shop. (I think she may make more profit on those things, than on the quilting machine.) Another big thing IMO, is the convenience factor - will you have evening hours, or only day-shift/office hours. Since I work day shift myself, finding time in the late afternoon/evening would be a high priority.
For me, however, there wasn't much difference in price of doing my own, or having it done. By the time I paid for the initial class ($100) and the rental fee ($25 x4 hr increments), and the gas, and get on the wait list, it was cheaper to have the other lady quilt it ( and I had to drive right in front of her house to get to the LQS, lol). She does pretty good work, and she has a fairly quick turnaround time, her rates are reasonable, and she will even bind it, if I ask her.
Long story short, there are pros and cons to everything. You just need to decide if the headaches are worth the effort.
I think if you were going to do this, you would need to have at least 2 machines to start with, so that one machine wouldn't be completely tied up, in case you had someone who wanted some intricate quilting done, or if you had someone who has a longer learning curve. Lot of things to think of, but baby steps accomplish more than giant leaps into the unknown, I will just wish you good luck in your venture.