If you had BOTH COMMITTED to a price, place and time, then he stood you up. But it doesn't sound like you did. You admit you were too busy to call him back.
I had a guy hold a product for me based on my word. Stand up guy for sure.
On the other hand, if a long distance deal is under way but not finalized and then a local buyer shows up and saves the seller the hassle, I don't think it's all that bad. Just a bummer.