How much would labor cost to paint inside walls of 1200 square ft apartment?

If you supply the paint you should be able to get a good painter in there for approx. .60 cents to a dollar a sf. I'm painting rentals at present in one sheen, one color for $400.00 labor only. Best thing for you to do is have 2 or 3 painters take a look at your painting project and give you bids. Ask for references and pictures of their work. Any good painter will have an extensive number of both. Be sure to check (call) the references to see what they have to say.