Check out PayNearMe - perfect for unbanked tenants and costs you nothing. 

Consider what works for unbanked tenants who can send money orders or for older or non-technology types.  

Just depends on what the situation is exactly there but perhaps a better word to describe this type of REAL estate may be unbankable.... not unbuildable.

I am currently personally un-bankable, so deals have to come from cash, partners, or their own financial merits. 

The unbanked can get a pre-paid debit card at walmart or circle K as long as the card permits ACH debits it should work.

sorry- when you become unbankable! 

You need to fix whatever it is that is making you un-bankable.

Distressed house unbankable with significant discount if purchased quickly with cash? 

I keep having bankers say “be careful with reporting losses on your taxes because it could make you unbankable.”  

Stopped accepting cash a few years ago, but some unbanked tenants paid by cashier's check, which often wouldn't be accepted by ATM (or phone deposit).Now, I ask whether or not they have a bank account on my application (I won't rent to them if they're unbanked - because if you can't manage a bank account, the rest of your financial life and your ability to pay rent on time are likely compromised).