Seen this way, the iPad mini's price points make a lot of sense as being parallel to the iPod touch: 32GB storage for $300, 64GB storage for $400…
And the capper, the must-get feature for the holiday season… an 16GB iPad mini for the magic $250 price point.
(The 4th generation iPod touch having now established a recent precedent for the marginal price of 16GB going to a 32GB device.)
The riddle of Apple's price structure is thus solved. The prices don't have to complement each other in a way that one becomes the upsell target for the other: they are in lockstep.