Sorry you missed out. There are a lot of WOZ’s out there and POTC is coming out soon that folks will need to fund. You will get one.
On your deal - Cuts both ways - you could have walked also and seller could be posting about you.
As a buyer I would send a say $500-$1000 deposit and say in an email “this deposit is non refundable and if I bail on purchasing you fully keep it. This is not a one way street seller can not sell this and return the deposit and cancel this deal without buyers agreement.” Both buyer and seller agree then send deposit.
If after seller bails on the deal after the deposit then call out their ass on him or her, even if they send the deposit back. They deserve it!
Of course folks will say that is risky for the buyer, but it will get you the game.