So what if a buyer backs out or changes his mind due to circumstances unknown. It's the way an online marketplace works. Put them on eBay if you want more of a binding-ish aggreement to buy. What would you have done if you agree'd to sell for $800 in a week while to buyer was securing funds and another guy offered you $1000 immediately? I know what most peole would do and that's the reverse of your situation. Is that ok?
Good luck selling but based on your responses/language, I'd be reluctant buying for you.