I don't mean to talk jewelry talk, but most people who work retail can relate this to anything really (especially if you work sales).
So I just LOVE it when a customer comes in and is comparing price of jewelry and then protests the price because s/he saw it cheaper somewhere else. HELLO! Not all things are alike! I may sell a certain size and quality stone for more because it's BETTER QUALITY than the pee-pee yellow diamonds the competition is selling. Besides, if you want cheap then why didn't you buy it there? I just LOVE asking customers that question! Obviously SOMETHING was stopping you from buying there...YOU figure it out and then let me know how you want to pay for this piece!
Or I love after Christmas gift certificates! I wasted an HOUR of my time on a woman who told me she had a $100 gift certificate to the mall and wanted to buy something in my jewelry store. To be frank, you DON'T get much for a hundred bucks...but I can show her a few items. After showing her necklaces, earrings, colored gemstones, rings....etc I finally tried closing her on a piece and she said, well I don't like it, it's too big. Then she proceeds to tell me she doesn't even have the GIFT CERTIFICATE ON HER! FOR PETE'S SAKE! WHY ARE YOU WASTING MY TIME!?!?!?! Then, she comes back the next day and my coworker sells her the ring that she told me was "too big"!

I'll NEVER understand people!