I'm excited about the prospect of networking with you and exploring potential collaborations! 

@Tracy Scott it's highly dependent on the deal, the type of property and the location.In addition to the items others have mentioned, here are some of the biggest potential start-up expenses that I study closely before buying a property:Foundation/structure--this is one of my few "deal breakers", I typically will not purchase a property with significant foundation or structural issues.

Potentially save on monthly cost of living while building equity in a fast growing market.

These small touches create a positive first impression for potential tenants.

If your fear is on a 30 year time horizon, then your lens should also equally look at the potential upside down the road over 30 years. 

How can I find a list of homes that are not currently for sale but that may have an ADU, so that I can start to reach out to these owners about any potential interest in selling?

That sounds like it would be your best bet.

The potential tenants that came for showings did not seem remotely put off by the rental price. 

I am looking to speak with a tax professional regarding potential tax implications of selling our former primary residence that is currently being used as a long term rental.

It happens.Recommend doing a thorough review of the area for actual tenant potential. - Build a profile of available tenant pool to be sure you understand their expected performance. - You don't want to rehab your property to Class A standards, but only have Class B & C tenants to choose from:(- How many rentals are in the area, where do the tenants come from?