As a seller, buyers wo say "next week" flake more often than sellers. Until you put money down, you have no claim
Totally agree. If it's someone I've dealt with before (and liked), of course I'll give some leeway and try to make the deal work. But otherwise - I'm not a store front, nor a dealer, and I'm selling for a loss. I'm always looking for the easiest, most efficient, low-risk, and hassle-free transaction as a private seller.
I don't care about your cashflow issues, or globetrotting schedule. That's more likely to make me just shut the conversation off. Let's get the damn deal done. Shoes reversed - if I'm the buyer, I'd pay the cash up FRONT, and ask him nicely to ship in a week (or whatever). I would make (and have made) the same accommodation as seller. But asking a seller to "wait till I get back, then I'll pay you" - is a bridge too far for a stranger.