Although the average of these 2 areas is around $950, you will clearly be getting very different rents in each of them.The more specific an area (and similar the properties) you can look at to compare rents, the better your estimate will be.

Upper Kensington comparing to "rest" Kensington and Philly generalI have difficulty finding a tenant to an Upper Kensington home that is well maintained (new wood floor etc) and furnished.

I'm not sure how helpful a traditional market study will be.

@Brook RiemanI think you need to run the numbers and compare to another investment types..

What is the best option for us since we will not qualify for the traditional purchase with using credit score?

@Eric Gardiner I'm still kind of new to this stuff so I am open to advice, but I think we will be using traditional financing. 

Condo appraisals require comparable  properties outside of your project.

If I have $20k to invest in a rental property, are there ways to get another loan for less than the traditional 20% down?

As a fellow west coaster, I understand how difficult it can be to find local returns that compare to some of those found in other parts of the country.My favorite part of your whole strategy ... training up your boys and teaching the next generation ... those memories and lessons are worth more than the paint and plywood. 

Traditional lending is too expensive here, so private lending or partnerships may work.