Depends a lot on how much woodwork or trim there is to paint or protect, special floorings that need special protection, and how much furniture moving, etc there is to do.
You can get a totally empty house that is going to be refloored (therefore, floor does not need protection), with trim being painted same as the walls, single-coat painted for as little as $0.35-0.50/SF. (measure up all the square footage of ceilings and walls to be painted - not the real estate square footage of the house). With split color on the walls and separate colors (or varnishing or clear finishing) for the trim or two-coats (not same color as original), a number around $0.80-1.00/SF would be more normal. If refinishing woodwork, doors, etc also - more usually $1.25-1.75/SF.
This assume no preliminary repairs to the walls - i.e. that any holes in the drywall have been filled and primed. For a normal house with a scattering of thumbtack and wall hanger holes (no large holes requiring drywall patches), add another $100-150.