I was lucky enough to know a LAer who introduced me to a Longarm Guild in my area. I went to the monthly meetings and learned so much about what the business is really like from listening to the roundtable discussions. My suggestion is to visit your LQS to see if such a guild exists in your area. Your LQS most likely contracts with a LAer to quilt for the shop. Get a number and talk to the LAer. Join as many online LA forums as you can find. There are several Yahoo groups for long armers. There is also an APQS Yahoo group. Quiltropolis also has a group. It's really important to get as much "real life" information as you can. Not only about the machine, but about possible "trouble" quilts and how to work them, pricing, licensing, wholesale purchasing, advertising --- the list goes on. So arm yourself with as much information as you can to help you with your decision.
Longarming is fun, rewarding work. I really am glad I chose to get into it. But the bottom line is that it IS a business and you have to treat it that way.
One final bit -- for me, my work is sort of seasonal -- I am busiest in the spring because of quilt gifts for graduations and weddings and in the winter because of quilts given as Christmas and Chaunaukka. So the business can have "fat" times and "lean" times. The business is solely based on customer demand.
Best wishes with your venture. If I can be of any help, feel free to PM. If I have bored you to tears with my bloviating, my apologies.
Ruth