Upgrading and Price
Here's the thing about price and the ability to upgrade: Apple computers have spectacular resale. The community of users is growing every day, and the warranty transfers with the computer (always buy AppleCare).
I just upgraded my iMac by 3 generations for $400. I can usually upgrade my iPods for less than $100 after selling the old one on eBay. That's the easiest way to get a faster computer with more drive space!
Sometimes you luck out and they discontinue a product you own...at that point the used price jumps above original retail. Check out the old iSight cameras and iPod Hi Fi speakers on eBay.
Service
Just a quick note on their service... I sold and old iMac to a neighbor who started having major issues with it. She brought it to the Apple store 6 times, because they couldn't get it to work. On the last trip, they handed her a brand new, 20" iMac to her amazement.
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