While I can understand your frustration with the seller in this situation, the buyer owes no explanation to anyone. They saw the cue for sale at the right price and they bought it. They weren't privy to any "behind the scenes" Pms or conversations.
One thing to remember too, is that there is no contract until there is a "meeting of the minds" of the parties involved. You can't simply say that the offer was close enough to know I was a buyer. There has to be an offer and acceptance of that offer before it's a done deal.
I had the same kind of deal with the late Raist Chin (R.I.P.) on this forum where he was interested in a Titlist that I had. I advertised the cue and he asked me about the price. I quoted him the price and instead of him saying "I'll take it", he asked for more pictures and said that maybe we would trade a cue that I had wanted from him, but there was never acceptance of my offer. The second person called me up and said they would take the cue and asked me for my Paypal ID. Raist got back to me sixteen hours later and was furious that I'd already sold the cue. In Raist's mind, there was obviously a deal, but there was no "meeting of the minds" on my part. Unfortunately, miscommunication ruined our relationship and we never did another deal before he passed away.
I learned my lesson with that deal and now, I'm almost anal retentive with asking questions and making sure I know the intent of my customer or seller before I make assumptions. I think 21's intentions were much clearer than Raist's because he at least mentioned the Paypal payment and I'm sorry it didn't work out better, but c and c was certainly not the cause of the deal going bad...
Steve