I've had a similar thing happen to me - I thought the sale was 'under discussion', as the seller had provided his paypal address. I had then asked for the seller's address and phone number before I made the payment, and indicated I could pay within 24 hours. Well, no response to that request, and I wanted the item, so I paid anyways a few hours later (the seller had good feedback), and the seller replied 'sorry, it's sold' and refunded me my payment. I was a little annoyed, but I didn't think it was a situation for negative feedback.
To me, the problem here is not the seller's policy of 'no funds, no deal', which I think is perfectly fair, it's that both parties are playing the game by a different set of unstated rules, and there is no communication to indicate the difference in understanding - the buyer thinks the seller is dealing solely with him (as that is how he understands the informal rules to work), especially when a paypal address is provided, while the seller views the situation very differently.
Maybe a good way to rectify this problem would be to state in the FS Post, for example, 'first to PM and pay within 24 hours gets it', or 'first to pay gets it, PM order not determinative'. That way, the rules are clearly on the table, and everyone understands what is expected.
Personally, if someone tells me they're definite and they'll pay me within, say, 24 hours, I give them the benefit of the doubt. I've been in that position before, and several sellers have operated by this policy to my benefit, so I don't mind returning the favour (in a sense). So I guess my policy is, first to PM me gets the item, as long as they can pay within a reasonable time; if not, I move on to the next aspiring buyer. However, I understand the opposite policy, and don't see anything wrong with it, as long as the seller makes it clear what is going on.
