Do your best to be professional and assure them there is no way they can lose money.

If you're on the inside, you stand to gain, and if you're on the outside, you stand to lose.

Pulling cash from your personal residence is certainly an option, but you must be careful - if your investment goes bad and you lose money, you will be stuck with that extra payment.

Instead, you could lose money.

Get a lawyer to clear the title and if those taxes haven't been paid yet, pay them immediately if you don't want to lose that house. 

I would rather make 0% interest instead of way over paying with a premium bidding state where I lose $$$ every time there is a redemption. 

I don't want to lose a deal waiting for an appraiser! 

Second, all I have at risk of losing if I walk away from the deal is the cost of inspection and appraisal. 

If I chose to push it, he could not only lose the sale but he could be subject to an ethics violation.

You pick some scenario that most people won't qualify for, advertise that, knowing you will lose money on that minority of transactions, and jack up the pricing on the commodity stuff that normal people actually qualify for, to make up for it.