I don't think either Southlake or Frisco are good rental markets. 

I'm looking for ways to invest in up-and-coming markets in Southern California, such as in San Bernardino County and Riverside County.

Tremont is an excellent area with really high market rents and super high demand.  5000+ sq ft. is huge too, congratulations!

I won't be out-marketing anyone. 

Did you guys ever raise private money?

Are you looking for properties in your local market? 

Learn your market inside and out—know property values, motivated seller strategies, and how to analyze deals properly.

I have a friend/neighbor that wants to sell me his house below market value so he can move back into an apartment and travel.

This is such an easy way to stand out against the competition in your market.

However, the property’s cost basis (what they originally paid) carries over to you, meaning if you later sell, you may owe significant capital gains tax on appreciation.Alternatively, selling the property at fair market value eliminates gift tax concerns, but your in-laws may owe capital gains tax on any profit.