I recently bought a 27" i5 iMac with the base 4GB of memory. I later bought 2 4GB stickes (8GB) total for about $50. I could now buy 16GB for about $120 and keep my 2 4GB sticks for 24 GB total. Why on Earth would anyone pay over $500 to Apple to upgrade from 4 to 16GB (4x4GB)??? Is Apple just marketing to stupid people? What am I missing? I could see paying a "little" more to upgrade, but over $500??!! That's just nuts!