You should have asked to speak to the owner, and then beat his ass in his own store.
Instead, you taught him an important lesson: that kinda thing is acceptable behavior.
Obviously the kind of storeowner who'd do anything to make a quick buck.
Whatever. I know a lot of you will disagree with me and I know this is not "punk", but I don't see any problem with selling something for "the going price." If I had a pair of boots that I could sell at Buffalo Exchange for ten bucks or sell on Ebay for 100, it would be retarded of me not to put them on Ebay. It's not his fault that you idiots are willing to pay $50 for this record, and as long as people are willing to pay that, I see no problem with selling something at that price. We live in a world where we have to have money to do simple things like eat and pay rent, and if other people have extra money to throw away on stupid shit, I see no problem with taking it.
The only problem I have with this situation is that the dude retracted on a verbal contract. That's a shitty move.