These numbers are from a 2006 costbook and they aren't adjusted for your area, so be careful with them.
These are from the commercial section and assume enamel on the walls.
Wallboard Ceilings (not popcorn) Per SFof surface with 2coats water based acrylic latex materials and labor: Brush $ .61; Roller $ .45; Spray $ .32
Wallboard Walls, 1 coat primer, water based: $.29; $.20; $ .12
Wallboard Walls, 2 coats enamel
On the residential side subcontractor rule-of-thumb which includes equipment, material, labor, overhead and profit for an economy job with 1 or 2 coats and little brushwork: $1.90 perSFof floor area
Good Quality, 2 or 3 coats: $4.35 perSFof floor area
Again, there are a lot of variables like how much trim and whether or not there are different colors, etc. But, maybe this helps.