We do very similar value properties. Our average all in at the end of 2015 was in the 38K range, but our average rent was $700 per month. We calculate ROI unleveraged for all of our properties to keep from calculating different properties differently based on house to house financing. At the 50% rule that gets us to and 11% return although in reality we do significantly better than that as we manage our own, and have lower vacancy, and repairs than we use in our models (5% vacancy and 5% repairs).
All that said I agree with @Account Closedthat $100 is not enough. I know other people use that but here in Northern Indiana you can do better if you shop right and screen your tenants well.
One other thing, I started keeping rentals in the spring of 2014 and we are up to 16 now with three more to be ready in March. My goal at the beginning was 100 houses which in my mind simply calculates at 100 X 700 monthly rent X 50% rule = 35,000 a month in pretax income (again this is unleveraged) so for me to hit your 100K a month I would need 300 houses. Run at that goal though. Heck if I only get to 50 I will still be living large. Right now though every penny and then some goes in to new units.
Good Luck