I'm having a hard time seeing how you were the victim here. Sounds like he was busy, thought he had what you needed, but didn't have the time right then to search for it, so he said he'd call you back. You called him three or four times within a half hour bugging him about the part, and you pissed him off. You can't expect the guy to drop everything for you, especially after you've indicated that you're gonna dick him around on the price. Sometimes you have to read between the lines; "I'll call you back, I have to look for it," often means that if you're in a rush, maybe you should look elsewhere. Then you go looking for a confrontation and you got one. What did you expect?
Yes, customer service goes a long way, but there are still plenty of businesses out there that will put you in your place if you walk in with an arrogant, "I'm a paying customer, my time's more important than yours," type attitude.