the price can always be adjusted based on on or off season, amount of colors to be used. A job like this can be done in 2 days and much quicker with a helper. I charge a bit more than others just because its quality work done professionally. Theres others that charge more than this just because they can on the on season and most people dont get a 2nd bid... http://youtube.com/watch?feature=youtu.be&v=b6_WEt9k_Hw
To paint a large section without leaving lap marks, roll the nearly dry roller in different directions along the dry edge, feathering out the paint as you go. After completing the entire length of the wall or ceiling, move to the next section and paint over the feathered edges. For the second coat, apply the paint in the opposite direction. This crisscrossing paint application sharply reduces (if not eliminates) lap marks.