You may find that the payment was made directly to the tenant; you may find it has not yet been funded. 

If they do, your best bet is a local community bank that funds these types of properties.Another option is a private lender but that money will be pretty expensive, as mentioned 10%  + 

Looking to get that cash back as soon as possible to use it to fund my business.

Doesn't sound like it would be too difficult to get funded.

There is a catch - the couple wants to 1031 the funds into their sons next larger project which is TBD.

If you do sell, think about where you’d put the money, whether into more passive investments like index funds or REITs, or possibly diversifying into a different market with better opportunities.If you decide to keep renting, you’re in a pretty solid spot right now.

I’m about to launch a fund and start building new builds.

I am stating out with wholesaling and once I raise enough funds will be investing in rental properties and flips.

I agree with the others here that say you need to have some skin in the game, if you are going to live there yourself, get an FHA loan rather than owner financing, you can get a 3.5% down loan, personally I do not love these as they require  PMI which is an additional expense, and you also need  bring additional funds for closing at least for taxes, title, attorney and transfer fees . borrowing from anyone else for the down payment, to include a personal loan from the bank is not a good idea, those again will be higher int. rate.

I am hoping to pull from a HELOC soon with funds up to approx 125K available to me through that.