I am just running across this question, I hope you see the answer... but I wanted to weigh in. I not only work in the 28117 zip code, but I live in the 28117 zip code. To answer you question, YES there are many homes not in subdivisions in this area... lot's of really nice areas.
If you would like to see any, just let me know and I'd gladly email you some listings...
I hope you were able to find a place. If you are still looking please allow me to send automatic info on available homes not on a subdivision. Please contact me at your convenience.
I LIVE and work in 28117...yes, there are many homes not in sub's in this area...granted, there are sub's but there are homes in this zip code not in them as well...
Like I said, I live and work here, I KNOW this area well...I'd gladly e-mail you some listings if you'd like...contact me at my website below or via e-mail at email@example.com
Good luck with your move...