I think that Apple has a good reason to avoid this strategy.
First of all, have you done the math on the $7 deal? MBNA America offers the deal, and it's an incredible rip-off. They have an agreement where you only pay interest (no principal) on the loan for the first 24 months, then you pay a larger minimum payment. That means that after paying $7 for 2 years, you haven't paid a cent on your iPod loan. Assuming you pay $10/month after 2 years, you'll have it paid off in a total of 76 months for a total of $686.96 in payments (for a $299 ipod; the interest rate is 25%!). By the time you pay it off, the current iPod will probably be the size of a quarter, hold 1 zillion songs, cost $50, and automatically sync with the digital music player in your flying car :)
But much more importantly, during these six years in which you're paying off your iPod, what happens when it breaks? the iPod has a 90-day warranty. That's covers you for the third payment out of 76. There are going to be some very angry people who are stuck paying $7/month for the next 73 months on an iPod that doesn't even work!
What Apple Won�t Tell You: Get An iPod for $7