My interest is mainly in accumulating rentals for cash flow. 

In these 7 days of insane roller coaster, we managed to arrange some hard money for financing, set up an appraisal to estimate a property we hold for the purpose of the loan approval, arrange an inspection, meet 2 contractors and crunch the rehab numbers so they make sense, find out that the lender can not 100% finance the deal as hoped, get discouraged but somehow, on a late-night phone call arrange some cash from a family member, and all that only to discover a day before closing, that the seller had $140,000 of liens against the property..The deal fell apart. 

Price $430kGOI: $52,200Taxes + Insurance: $14,600Vacancies / Gas Heat / Maintenance (estimate): $8,250On-site property manager landscapes and repairs for discounted rent. 

I could be wrong but that is always what I have used for expense estimates.

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.Download BP’s newest book here some good due diligence in Chapter 10.

Scott The Book on Flipping Houses, The Book on Estimating ReHab Costs http://www.biggerpockets.com/flippingbookGood LuckPaul

The owner pays the county (or city) and the county or city sends you a check.Nationwide about 3-4% get foreclosed would be my estimation. it is probably lower than that in Howard or Montgomery county.

@Jason Chopin How are you estimating the costs for insurance?

All I have is a super ballpark estimate from an architect friend (at a high-end firm so maybe his number is inflated?)

It's good to have reserves, it's better to not have surprises ;) as for an exact dollar amount you can accumulate less per property as you acquire more.