If it's the one with the smaller harp size (9"), be aware that many people get frustrated with the small amount of space left to quilt in once you get to the end of a bed sized quilt. That may be why the one for sale got used only twice. It's fine as a beginning frame setup, especially as a transition from quilting on a domestic machine, but most who like frame quilting upgrade as soon as they can to a machine with a larger harp.
You should probably decide on your budget first. That will eliminate or identify lots of setups. For example, if you can spend $20,000 or so then I would definitely recommend looking at an Innova. In general, no matter what machine you are looking at, you want the machine and frame to work together well. This usually means purchasing them at the same time.