While I can appreciate the frustration, I learned pretty quick most people are not going to wait for your schedule. On the same note, I don't want to wait too long when selling either (lots of flakes out there).
On a couple purchases when I knew I couldn't come for say 2-3 days, I asked if they can take a deposit of say $100.00/$200.00. Just to show I'm serious and that I'm not going to bail. And if I don't come by x date, that deposit is yours.
It's just how it is, frustrating or not.