Here's my idea...
Joe goes onto iTunes wanting to sign up for the new iTunes Rentals service. He goes to the normal iTunes page, with a new rentals button on top. He clicks it and signs up. There are three plans. For $9.99 a month he can have as many songs on as many iPods, but only 2 computers. For $14.99 he can have the same as before, but up to 5 computers. And for $29.9 he can get all the stuff for $14.99, but also be able to burn 20 songs to CD per month.
Joe signs up for the $20 plan. The button next to his log-in information now says instead of "By Song" it says "Monthly Plan". Joe now downloads as many songs as he wants and puts it on his comptuer and iPod. He can download whole clebrity playlists and iTunes Essentials. Now, Joe can burn CDs too, while he never could burn 20 songs a month, but it gives him the option.
When he decides to cancel his subscription 18 months later, he now has the choice of keeping all his songs, or some of the, for a set price per. He downloaded 2,300 tracks over the last year and a half, and he wants to keep 1,001 of them. Apple offers to let him keep the rights for the songs at $.65 per song if under 50 songs he wants to keep, $.50 for each song over 50 he wants to keep but under 100, $.40 for each song over 100 songs but under 500, and $.30 for each one over 500 but under 1,000, and finally $.20 for over 1,000. So now Joe buys the rights to these songs for $200 dollars.
Now, as Napster says, do the math.
$20 * 18 = $360
$.20 * 1,001 = $200.2
$360 + $200.2 = $560.2