I found a site that claims to provide the latest salary information for just about any job title in just about every city in the U.S. It is at Indeed.com, a job search site. Typing in "Photo Stylist" for Los Angeles, CA I find that the average salary is $44,000 a year. How does it know? I suppose it searches through all the data with the key words and comes up with the relevant salary. I tried "Food Stylist" for the same area and found that to be $59,000. Since we mostly freelance it's tough to say what a "salary" is but it's still fun to experiment with this site.
Here's the link to Photo Stylist in LA, as a starting point: Indeed.com. What do you think? Is it accurate for your market?