The wasted time is the worst. If I tell a seller I'm coming and I indicate it's a bit of drive, I expect the courtesy of having them wait for me to get there before having someone else come over to have a look. I've never had the exact situation you faced as I normally bow out once I hear things like "first come, first served" or anything else that makes me think it's going to turn into an on-site bidding war, especially if it's more than a few minutes a way.

I did have a seller tell me that he'd contact me about a game if the first guy that responded didn't want it. He called and said I should head his way and gave me his address. I told him that he was about an hour away, and that I was leaving immediately. About 45 minutes into the drive I get a call from the seller. He proceeds to tell me that someone just came and bought the game. I asked what was going on as he knew I was on the way. He told me he scheduled someone else to come "just in case" I didn't show up. Obviously, that guy got there before me. I asked him what would have happened if we would have arrived at the same time. I think he said something like "we'd have figured it out". I gave the guy a piece of my mind and then turned around and went home. For a second, I was really tempted to drive to his house so I could meet this jag-bag in person and to see the condition of the game. I chose not to. I then went back to my mantra "no deal is better than a bad deal" While that game may not have ended up being a bad deal, I feel like it was probably better that I didn't get that game. There have been plenty of games since then, so always remember, there will be other games.

OP, considering you didn't crap on his lawn or run his mailbox over, you might want to send the seller your contact info and ask him to forward it to the buyer, just in case the buyer wants to get out of the bad situation he's going to find himself in. Worst thing that could happen is that the seller doesn't forward it on as he already has your number.