I estimate it would take 30-40 rental units to need to spend 750 hours a year managing them.  

I estimate my crew and I can fix it for (3k).

Scott The Book on Flipping Houses, The Book on Estimating ReHab Costs http://www.biggerpockets.com/flippingbookYou might consider Niche or Specialized Housing like student housing.

Do you know the exceedence interval that estimate is from (e.g. 100-Year Flood = 1% chance of water reaching that elevation in a given year)?  

Things like local renter density, vacancy rate, rent estimate, etc..  

Anyone here use Xactimate or similar to estimate rehab costs?

Scott The Book on Flipping Houses, The Book on Estimating ReHab Costs http://www.biggerpockets.com/flippingbookConsider checking out HUD homes for small multi's owner occupied gets first crack.

That always helps when estimating rehab jobs.

Scott The Book on Flipping Houses, The Book on Estimating ReHab Costs http://www.biggerpockets.com/flippingbookConsider checking out HUD homes for small multi's owner occupied gets first crack.

Essentially, the Good Faith Estimate is combined with the Truth in Lending (TIL) disclosure, now called the "Loan Estimate," and the HUD-1 settlement statement is combined with the final TIL, now called the "Closing Disclosure."