I remember reading something a while back about still lives mainly being bought by women in the 30-60 age range, if that helps at all! I can tell you that almost all of the still lives I’ve sold have gone to women- the only exception I can think of is one man who bought two paintings from me last spring, he told me that he was a keen cook and enjoyed having paintings of fresh veg to inspire him. But the vast majority of my buyers (across all subjects in fact, not just still life) have been women.
I only really sell online- I haven’t had much luck with local shows yet- but from what I can tell through email conversations with buyers, most are old enough to have grown children, and often grandchildren. Younger people, here in the UK at least, are struggling to save up for homes, cars, and pay off student debts, so they’re unlikely to be buying non-essentials like art.
I’m still an art student, so I paint whatever strikes my fancy, post it online (DPW, on my blog, pinterest, and my facebook page- and instagram, when I remember) and see if people like it. I’m still figuring out what I want to focus on going forward- and how much I want to pin myself down to one style or genre, for that matter- so I don’t worry about marketing to a specific audience, at this point. Once I’m done with my degree, I’ll probably start narrowing it down and looking to target a more specific audience. I see this as a research stage!
Sorry I can’t be more helpful- hopefully you’ll get some responses with more reliable info and stats!