It would have to be an unusual situation that makes the cheaper method of acquiring the money unfeasible.So for real estate where I am active, I want no less than 14%, and that's ON TOP OF the management fee (10%) that I pay myself. 

-Cheaper to buy outside of major cities or into cheaper markets/states-Build a portfolio of becoming a BIG fish in a smaller pond by investing in smaller markets-Take advantage of the Vacation Rental markets.

Those are just some options of cheaper markets and all have airports to fly into to make an easier commute. 

For example, say I were to pay myself a salary of 15k annually for property management, I could contribute this 15k to a solo 401k and decrease my overall taxable income by 15k?

Problem is they are looking on the cheaper end , less than $ 375,000. 

Cash is cheaper.

The problem is that I'd have to hire a cheaper manager, cheaper maintenance, cut marketing, do less remodeling, etc.

The cost of living on campus isn't getting cheaper.

From the standpoint of building wealth as a younger investor utilizing a taxable account, it seems that investment properties offer better opportunity early on because (i) they can be used for leverage and (ii) depreciation creates tax advantages that go unrealized in a non-taxable account (i.e., a self-directed IRA).

A minimum tax of $100 is due, but you may owe more depending on your federal taxable income and your net worth.