There's a good lesson in this. If you want something tell someone you want it. Don't equivocate, just say you'll take it.
Once you and the seller are mind melded on that fact you can work out some reasonable terms, like I'll come and pick it up this weekend. I'll pay you the agreed price provided all is as you described, otherwise we can discuss it in person.
Boom, done.
It sucks to lose out on a deal, been there! But you should learn from them so you don't kick yourself next time.