Salary Expectation. Help?

I'm getting ready for a phone interview for a job I really want. I can't get an accurate answer looking on glassdoor. It's an outside sales representative position for medical sales. (DME). Looks like company is trying to build market in my area and they don't have any existing business here. They are 21 yrs old from southern california. I'm in central California (not sf bay area)

usa jobs
usa jobs resume
usa hotel jobs
usajobs
usa jobs federal government
usa job in ksa
usa jobs
usa jobs login
usa jobs gov
usajobs.gov
www.usajobs.gov
usajobs.com
usajobs
usajobs.gov official