I don't work in HR, but while I was an Intern at one of my jobs I sat in a cube right beside the lady who did all the hiring for the company (company had roughly 40 employees at the time and was growing fast, so didn't really have a department, but she made alot of calls.) I couldn't hear the other end of the line, but she would on frequent occasions say "we can't meet that sort of salary, you need to look at CA or maybe the east coast if you are expecting that." (This business was in Las Vegas.) I would also hear her give broad ranges at time, but it usually was more of a "we cant meet that" or "we are a smaller company, ...."
This woman wasn't the one that decided who to hire, she didn't even do the physical interviews, she just was the one assigned to setting up interviews and screening people before they came into the office (make sure they are actually interested, where they live, ect.)
My recommendation is if they live in the same town, then the worst case scenario is that you waste a couple hours of that person's life. I imagine most people that are applying for a non-profit organization (Specially that size) should expect a pay cut, and would do it out of passion or want. If they live in another state then it may be polite to say something along the lines of "We are very interested in bringing you in for a 2nd interview, but I don't want to give you any false impressions, we are a small non-profit organization and we won't be able to meet your current salary."