Check out Bryan's article for some more commentary and references.
I find the iPod pricing structure devilishly clever. It kills me:
Model Size (GB) Cost $/GB Shuffle 0.5 $99 $198 Shuffle 1 $129 $129 Nano 2 $199 $100 Nano 4 $249 $62 Mini (disc.) 4 $199 $50 Mini (disc.) 6 $249 $42 iPod 20 $299 $15 iPod 60 $399 $7
Let's ignore that last column for now ($/GB). We'll work our way down. Suppose you are interested in a Shuffle. You get double the songs for a mere $30 more. That's a tough upgrade to ignore unless you really lock into the first model being sub-$100. Don't worry, it gets worse.
Suppose you were interested in a Nano. Starting at $199, you are damn close to a full blown iPod. For a mere $100, you get ten times the space! Ok, ok so space is important to you but not that important? So you move up to the larger Nano (4 GB). Whoops, now you're only $50 away from the real deal—might as well upgrade right now. We had basically the same problem with the Mini that this model replaced.
Tomorrow I'll discuss a few ways you can talk yourself out of (or maybe into) these upgrades.