You must be rich. If you like to throw your money away into Apple's coffers, fine with me, it helps keep them in business so they can keep making Macs for me to purchase now and then. Just know that they charge HUMONGOUS premiums for added-on RAM, HDs, optical drives, etc. etc. Always have, always will.
I think even the most biased fanbois go to macsales.com or newegg.com for their upgrades.
You have to be a complete tool, or so wealthy that losing 5000 dollars on the street would feel like me losing 5 dollars, to pay for their RAM/HDs.