I just sanded floors in terrible condition. I rented an orbital sander 18 by 24 and used 4 grades of paper from 36surfact to 120grit. I used a palm sander for the edges. Its a big job, but not too difficult, just time consuming. You can take off alot of wood without going too deep. I then put 4 coats of Polyurethene Satin finish waterbase type. I wonder what a floor refinisher guy would have charged?