$15 an hour, this is a person that might be retired and has nothing else to do, or a kid that this might attract, BUT, this is definately not a painter. I do hope that you do not get a big surprise when you return home. You might get a $15 an hour result.
Here is how I work and I am a painter. I compute the square footage of the total surfaces that I will put paint on. Then once that is computed, I will multiply that times $.57 a square foot. that will be labor. Then divide that square footage time the coverage per gallon of paint and that will become the gallons required. Remember, you said that your home is about 600 square foot, but that has nothing to do with paintable surfaces. Normally you can multiply the square footage of a home by 3.5 if painting the ceilings and 3.0 if not and that will become your paintable surfaces.
So, some fast math: 600 square foot home and painting the ceilings becomes 600 X 3.5 = 2100 square foot X $.57 = $1200 in labor only. Then 2100 divided by 250 = 9 gallons of paint @ $23 a gallon.
I think you can see the differences. Remember, you always get what you pay for. Keep this in your mind.