It probably doesn't include income from the 5th or 6th unit if it's supposed to be a loan for 4 units right?

Moving away from direct property ownership to becoming a limited partner (LP) in larger syndication deals can drastically reduce your liability and improve scalability.

Maybe they mean your net, net income? 

Could the rental income justify the price?

I offer them a lump sum and monthly income.  

I am starting from ground zero, with no prior background or capital to invest, but with a strong desire to create passive income for my family.I currently work as a middle school teacher in California, and while I love my profession, I have a strong desire to explore avenues that could potentially provide financial stability and additional income streams.

If you're not offering any commission, you may see reduced buyer activity on your property, or you may get unrepresented buyers, and they may not be fully qualified since they have not been vetted by a buyer's agent.

U want your parents to talk to their CPA FIRST.. if they go the development route they are now ( depending on the amount of units) creating inventory.. which will be taxed at ordinary income rates ( very HIGH)if they just sell they can 1031  and move on to something else.. many times when you run the math consider the risks of a partnership.. the sale of the land is far better than thinking your going to make some profit.. 

A PUD zone would allow this type of flexibility and might get you reduced tap fees akin to a condo rather than SFR.  

If you're seeking a reliable income stream, consider checking out Cleveland OH.