You need to ask these questions of the place you have doing it.
I buy the paint. I don't like the cheap paint that they use. I buy the Marquee and it's $45 a gallon.
I just had my hallway painted (from front door down to family room and up the stairs to the bedrooms) I have a split level entry and it was $700 - this included dry wall repair and painting. They removed the pictures, spackled the holes, and such.
Our family room which is 30 by 25 was done for $300 - why so cheap?? Because I had had water damage so the room was totally empty and they didn't have to move anything or bring in drop cloths, etc. Again - I paid for the paint too.
Your area will also determine your price. Go to Groupon or Angie's list and you can find deals.