This is a tough one, and there is no real answer for you. It comes down to overhead, experience, and product, and where are you. If your guys can paint the room in an hour or they need two days for walls, your texture guy started yesterday or has been laying texture for 15 years. What your overhead is and where you are at also count into the total, this is where most new companies go belly up. You should never take a job you can not bid. I could tell you .25 cents per sf and that may work for me one guy, no crew- no over head, but you need to make a min of 3.50 p/sf. How much your hourly cost is and your crews speed play a big factor in your bidding. There is no magic number. It is all in how much it costs you to run for an hour then how many hours you will take. Then add your profit and bingo you got your cost. Best of luck but I recommend never taking a job you can not bid, sub it out and work with the contractor and learn. Then someday you will be ready for it yourself.