we have arranged it though!
Just my thoughts on it :
Until money is changed hand, very few people consider an item sold. It's mainly due to time wasters, or people that change there mind beforehand or once they have seen said item.
Also if you agree a price, via PM or what ever, but can't collect & pay for a few day then a better offer is received, many people will take the better offer. And why not? If it's not a personal friend you're buying/selling to, then why not except a better offer.
It's sad but true that first come first served, seems to be the way of ensuring that your item sells, and your not sitting round for people to not turn up.