Those holding cost will certainly add up over time and kill any cash flow.

Most of our clients are cash buyers.

The math behind Real Estate is not that complicated, Revenue - expenses and debt service = cash flow. 

I am of the opinion that you'd be better served using that money toward the down payment on a property.

What you spent on the land/lots can go towards your down payment and, if you've owned the land for more than 6 months, you can use the value of the property toward the cash injection requirement.

@Rajesh Kasturi My favorite MTR market for cash flow AND appreciation is Portland, OR. 

How long have you owned these, and how much is rent vs the payment?

Understand how to "add value" to the property and evaluate cap rates, IRR, cash on cash returns. 

We bought it in cash with 9 investors for a total of 970k contributed.  

Good luck with getting this tenant to accept higher rent, because you've trained your tenant to think they have a "mortgage payment" that never goes up!