Your renovation costs could easily be $100,000.

Some things I do to avoid bad situations: screen well, only have properties in good locations where people actually want to live (I find tenants behave better when they know they have a good thing going for them and that they are easily replaceable), set proper expectations, have a rock solid lease, go over it with new tenants to make sure everything is clear and agreed upon, and enforce the lease by issuing a formal notice to pay or quit every single time rent is late by even one day (and charge the late fee), or a formal notice to cure or quit every time there is a lease violation.

.- Investment Lock-Up: While there’s a chance your funds could be tied up for a bit, if the property is well-designed and in a desirable area, you might see appreciation that allows for refinancing sooner than you think.Buying an existing property:- Less Risk: Existing properties come with a track record, so you can analyze their performance and potential more easily.

Do you have the knowledge and insight to handle any LT complaints and are you set up properly with your bank and security accounts and can easily collect the rent, etc?

We also chose the wrong property management company who promised they could turn SECT 8 units easily.

If possible, I would look at the building to see how easily I could merge 2 spaces together, providing a tenant a 1,400-1,500 sf space complete with a small 150-200 sf office w/bathroom, and the rest shop space.

If your friend recently made 3x his mortgage, but it was a spring/summer month, he could easily struggle to cover the rent in the fall and winter months. 

Now applying this to Philadelphia, you can easily go into areas of North Philadelphia or areas of SW Philadelphia just as examples and find properties that pencil as BRRRR's as easily as it is to pick produce out at a grocery store.

There can be a lot of details to this, and one can easily get lost in the details but pull-back and keep vision of the fundamentals as it really is rather simple. 

That could be found in the title search pretty easily.