@Richard C., @Patrick Donovan:
I don't think your numbers are very accurate for our area and this property in particular. As an area we are running under 5% vacancy right now (I think last year was 3%, and has been under 4% for the last 3 years consecutively). My properties personally have virtually zero vacancy (over the last 4 years I have less than one week total for all units combined, which includes 3 tenant turnovers).
I would also wager maintenance, repairs, and capex at more like 10% total on this place (assuming the HOA takes care of the yard and exterior structure/maintenance).
He also lives virtually next door, so paying 10% for management would be silly. He should be able to manage this place with very little time or cost.
Every property and area is different and none of us really have enough info to know, but personally I would guess worst case his numbers are more like 5% management, 10% maintenance/repairs/capex, and 5% vacancy (and I really think those numbers are way worst case). I am guessing his cash flow right now is closer to $300/month on this place. That would change if/when he moves or under other circumstances, but that is how I see it. It probably also didn't cost much to get into.
I think most local investors would jump on a similar deal right now, IF they could find one.