I am trying to locate an ion counter/meter so I can run some tests on ionic air filtering units and get a sense of the ionic charge coming out. I am not directly affiliated with a university or scientific organization, but want to do this to satisfy curiosity and think the outcome would be very insightful. Ion counters sold online are hundreds of dollars and out of my price range for a one-off experiment. If I wanted to test with an ion counter/meter, could anyone make suggestions on what industries/jobs types/companies to inquire about one? Ideally, some university or research facility would have one that I could use with minor training. I am in the San Francisco Bay Area, so I am hoping there would be something near by. Any leads appreciated.