This vary heavily town to town. 20% down is great if buying strictly as investment but if you have a way of owner occupying I would explore that route and apply the 20% down to increasing value of property and instead using low money down loan. 

Flip side, for a third of that you are trained to find properties using creative finance taking over existing low interest loans that cash flow and you are buying in decent neighborhoods with every day lunch box Joes that have kids and go to work and pay rent on time. 

I like strong MSA's, high rents, & low purchase prices, to maximize cashflow & cash ROI. 

On the low end, you had $1365 as the rent assumption. 

I bought this property with a private interest free loan from a friend. the person i bought it from need cash fast so i offered them a low cash offer and they accepted.I had enough money saved up to rehab the house with my savings.

Home last sold in 2007 for somewhere around $120k, currently could sell for upwards of $400k, so it's probably paid off or has very low interest rate.

HABD SAFMR states that a 2/1 with 2 people in property’s zipcode on voucher maxes out at $1356, current rent is $779, and when I search for comps on multiple platforms I see the low range being $860 and higher end of median $1150.

@Polat CaglayanI've never seen a formula but here is a general rule of thumb for multifamily:The class of an apartment refers to the quality of the building, which can be determined by a number of factors, including age, location, and condition: Class A: These are the highest quality apartments, typically built within the last 15 years.

The appraiser gave the house a low score so the bank said it is a risky investment for them and gave me a 70% loan.

The low purchase price was a big part of it.