I ordered memory from Crucial, and I’m impressed. They give you a neat little download for the Mac, that detects what type of memory your Mac uses, and tells you the options you have for extending it – at prices much lower than Apple.
They offer Special Delivery for an extra £3.50, which is less than cost. I didn’t take it, and my memory still arrived the day after the next working day.
It’s safely packaged, but small enough to fit through a letterbox. As long as it works, I’d call it a pretty excellent service from the start.