The best way to figure out the cost for this job is time+materials. How much time is needed for the prep, priming and panting? Spraying will be a great time saver but will require some extra materials (masking). The time saved easily offsets the little extra labor for masking whatever needs covering. Of course you need to own a sprayer or rent.
These are some of the considerations you need to take into account when biding any job. If you get the job and also get inventive with saving time and labor then that is money in your pocket.