Various non-professional longarm owners on the board, including myself, have posted asking about the pros and cons of renting time on their longarms. The majority opinion seemed to be that it would be a bad idea, because of the need for business liability insurance, risk of having strangers in your home, risk that your machine might be damaged by a novice, etc. In my area I am not aware of any shops that rent time on their longarms, but the shop where I bought my Innova in Ephrata WA did rent time.
I am not actually convinced that you would save much, if any, on the cost of getting your quilts done, or that you would be happy with the finished product, until you become very proficient at loading and quilting, and that takes some time - time that you are paying for in rental and instruction fees.