I've owned Macs for several years and always go through Apple and have had great experiences with their customer support. I bought a MacBook on eBay and it was still within the one year original warranty period and the battery was completely dead. Made an appointment with the Genius Bar and had the tech check it out, confirmed it was the battery, and then he handed me a new battery and the laptop was as good as new.
Sorry you had such a bad experience with Best Buy. I have never had a good experience with their customer support. I only buy small low-cost items there and only if I have to. There are other places cheaper with better customer support.