@Chris Hodge depending on where you live, there are actually companies/services that will take care of getting the information for you.

Your example is 101,750 a year cash flow over the 20 year period you mentioned....and as I noted you are basically eating your principal all that time and have little left when you sell at that point....NNN leases are out.From your example:"$2,035,000 Accumulated Cash Flow (NOI)If you put that same "seed" money into the stock market...or almost any other investment, that money is "parked" there the same way.However, if you used that same $2M as a 20% DP on a NNN worth $10M, with a minimum of a 6 CAP (I know, you want higher, I just focusing on the minimum you want) you would have a debt service of around $560k/year...which would get you your $30k.  

I would also budget for increased cost of goods/services in the future.

You can purchase 2-4 multi unit under Home possible for primary residence. 3% down payment should be seasoned and rest can be gift.  5% is minimum requirement  for Home Possible. 

If you have an understanding of real estate and think you can get better results growing your retirement savings in that asset class, then a self-directed IRA or Solo 401(k) is a means to do that.All investments are made in the name of the plan, all expenses come from the plan, and all return accrues to the plan.There are several different plan types and service models available.  

Their customer service/responsiveness during setup was a little lacking, but it's been smooth sailing since.

That does not include debt service, but does include taxes, insurance, advertising, lost rent to to vacancy or non-payment, legal expenses, accounting expenses, capital expenses (roofs, furnaces, etc), and property management.   

Do you recommend buying these lists from lead services that provide the addresses for absentees, etc?

Another weirdness that you may or may not face...many of the homes were continually having big wet spots appear in/on the slabs, hundreds of people, were calling leak detection services, thinking an underground plumbing leak was causing these mystery wet spots.

FHA loans will require a low down payment, and you'd be living in one unit while the rest of the unit(s) pay your mortgage.