Estimate a good painter costing about $150 to $200 per day plus materials. Cost will vary greatly depending on where you live. New York city will be more than some deep south back woods town in Alabama. You want a painter who will advise what you need done and one who is good and fair. Might want to check on references. Does the painter have to move a ton of shit out of the room or is the room empty? You could get the room done in 1/2 day by someone who will rush through the job but ask yourself what type of results you seek. Maybe you can do some of the work yourself? I would say do it all yourself and the end result will be a better job. Its not that hard and you could take the time that a hired individual can't afford to take. However, it your wealthy, pay any price and hire the best. FWIW!