Well, I feel your pain because it's happened to me, too.
BUT - I've sold any number of things on Craigslist and from local ads etc. If I had a nickel for every time I've heard someone tell me they'll take it and they're on their way, and then NEVER show up, nor even call....
As a seller, if a buyer over the phone says he'll buy it, I say "first come first served, just so you're aware" and you had to have approached it that way, assuming that it might be gone if it's such a good deal.
I will agree with you that the guy should have called you out of courtesy to let you know it was gone, thus saving you some travel. And he should have told you up front that it might be gone.
I mean, if I had something for sale locally that was a great bargain, and some guy says he can't be there for three hours, but meanwhile, I've got people waving cash in my face, well, cash talks really loudly, compared to hot-air blowers, which is what I, as a seller, have to assume about every potential buyer...
Sorry, but I've been burnt WAY too many times as a seller...