This does help to soften the valleys when the market falls though.

Right now you will find that you'll net much more than that as the rental markets are very strong, but over time, as real estate markets are cyclical, rents will soften and averaging around $100/door/mn over an extended period of ownership is not a bad goal.As far as financing your 100 units, it all comes down to liquidity.

Could also put in one or two parcels, a god-send of a well and septic, water softener, and a larger house ...

But at the same time, the rents for the top of the market properties are falling slightly and the Mueller model, which I use and trust, tells us that rental market softening is a leading indicator for a slowdown in the sales market. 

As the market softens (and it will at some point), the owners of the buildings bought recently at less than 1% rents with 80% loans will feel the pinch.

I'm seeing softening in the around $600k level here in Denver with one of my current clients.

C NeighborhoodBuyer says 3 Bed 2 Bath  1,120 sq ftAssessed @ 79kComps at 75kHas renter at 650 now Property Management in the area says rent should be $1,000, if the market softened $900.

West LA is softening a bit on demand. 

It did take me a while (Cambridgeport, 2+ months, tried to get 8/1 but had to get 9/1 instead) to rent my place at what appeared to be market rent so it could have been the water or it could have been a softening of the market.

@Eric Tait is right that if there is any softening at all, it will likely be felt first in commercial office space, as that's what was hit hardest during the Enron, et al. busts in the early aughts, although that was arguably about mismanagement unrelated to energy prices.Keep in mind that the major energy companies are ridiculously profitable at any oil price.