When I first decided to buy a long arm, I opted to rent time on one first to see if I was really interested in working on one before I bought
I paid about $100 or so for the first class. It included all fabric, machine and a teacher. It was about 4hrs long and we went over loading the quilt, tensions, threads, etc. Everything really. It was the best money I ever spent. So I strongly encourage anyone interested in buying a long arm to rent one.
The rental was $25/hr, and included the thread and machine plus support while working. I purchased the batting there and brought my own backing fabric.
With that being said, if you plan on doing mostly pantographs or simple all over designs, then rentals are the way to go. Doesnt take too long to learn how to do pantographs and they stitch up relatively fast. Now, if you have dreams of doing detailed custom designs, you may need to buy a machine. It will cost you more in rental fees than just sending it out. For a quick comparison, a simple pantograph on a throw sized quilt will take me about 2-3hrs from loading to unloading. For a custom design on same size can take me anywhere from 6hrs to 40hrs depending on the amount of detail.
In the end, I think renting a LA is a great investment in time/money. You definitely get your money's worth.