I have at least one lender and one agent, but would like to fortify those positions with other reliable sources as well to round out the Core 4.

@Robert Williams - Not sure which episodes but I know @David Greene goes in-depth on building your team and what he calls your core 4. 

The “Core Personal Consumption Expenditures Index,” a key inflation indicator, rose a faster-than-expected 3.1% in April as price pressures built in the rapidly expanding U.S. economy, the Commerce Department reports.

so I don't know if it's really a viable business at its core.

Most large metro areas will have deals in an hours drive, find a place you are comfortable with that has upward trajectory (jobs, population growth, market phase), build your core four and rock it! 

This is a very compelling example of why you should not close on a turnkey property until all the work has been completed. 

I have done apartments and self storage, so this is a little outside my core competencies, but if the price is right, I’d like to investigate it more.Thank you in advance!

-Erica DasIt does not matter where you start as long as you develop your Core 4.

You'll want to keep looking to build a "Core 4" team:  Agent, Contractor, Mortgage Lender, and Property Manager. 

That being said, finding the 4 Core (Deal Finder, Property Manager, Contractor, and Lender) is imperative.