A lot of extra unnecessary costs. 

________________Thanks Gideon, I will surely include the extra numbers to play it safe and so that the rehabber / end buyer will have all their costs covered, but I noticed you based these deductions from the ARV and not the asking price, do I make these deductions using the ARV from sold comps.?

Just as an extra thought.  

If you purchased SFH (with no HOA fees), then you would have that extra $150-$200/mo from HOA fees to go to increase your cash flow, save for repairs, etc.2) Have you considered using some of the excess money (current going to pay down the mortgage) and putting it into an account for each property to cover repairs and eventual replacement of items?

I need to pay extra legal fees and extra cash in bank account as guarantee. 

In the name of "going the extra mile."

I am only 23 so I don't mind waiting the extra year to get my first income-producing property, but rather house hack if the deal presents itself.

However, I couldn't have pulled that off and made a profit if I had paid too much when I bought it.Leave yourself extra "cushion", knowing that you won't be able to sell or rent at market prices, you will have to likely lower your price to do something with it.

Account ClosedNice job.Sure, you may have had cash in it for 220 days - but an extra $20k pre-tax, $15k (37% annualized) after tax is a good thing.

What kind of extra expenses does everyone take into account for the additional units, are there any economies of scale, how do your factors change?