Although I'm not in a similar boat I can offer my advice, which really counts for nothing but here it goes. If you have or planning to have a family in which you need some income, I'd say it should be time to start thinking of getting a steady job (there are still some out there, just maybe not in your field). However, if that isn't a problem I'd say keep trying! There are plenty of graduate students your age and older, I really don't see the big deal.