A lot of the big box hardware stores rent them out, if you haven't checked that option out already.
Many of the modern floor refinishers are pretty much 4 orbiting sanders on a base, rather than one big drum. My understanding is they are generally better for lighter duty refinishing. If you have very rough condition wood floors, you will probably want a drum sander still. I'm sure you could just use a hand orbiting sander if the floor is not in that bad of condition.