I use all hard surface flooring and budget for repainting between tenants.

Within 1 day of repainting the walls white and the cabinet doors/drawers dark gray, we found our tenant.

Maybe my best bet now is to go the route of mold/water block as Jim Shepard suggested and then repaint the ceiling for the tenants.

I've dealt with wood floors and lots of painting / refinishing stuff, repainting the walls and having the floors professionally refinished will completely solve it; make sure you have them actually refinish them and you will be fine.

The walls also need to be repainted so I'm not sure if there is a more or less cost efficient way of just buying paint at Lowes and putting it on the wall. 

If the units are smaller, that cost seems plausible, but would be on the lower end of the range here.Remember that is only the cost of the electrician replacing existing circuits and does not include the repair and repaint you will been to do to walls and ceilings (hopefully the electrician is not planning to surface mount).  

Their kids have written on the walls with crayons, the vanity installed 5 years ago has been scratched to the point it needs to be repainted (it is white and a lot of paint has been scratched off), the caulking around the sink and tile has turned black, the hardwood floors are extremely dirty and will likely need to be sanded and stained and the carpet must be replaced. 

This is for a house you're selling... what you want is to get the biggest "wow" factor for your money.Go white.. it's very neutral... if the buyers don't like white it's very easy to repaint.

More than once, I've had tenants call me up, asking if they can repaint this or replace the cabinet handles and whatnot, and I end up just reimbursing part of the materials on their rent.

Structurally they're fine, but they all need to be reglazed and repainted, and it's fairly obvious.