How expensive is it to legally fill an iPod?

I don’t know how many other people have done the math on this one, but I was thinking about iTunes and the new iPod when I realized that to fill a 40GB iPod (legally) from iTunes would be rather expensive.  If you believe the 10,000 song capacity, it would run $9900 dollars, plus the cost of the iPod.  Assuming that an average CD album is $12.50 and has 15 tracks,  it would cost about $8,330 dollars to fill the iPod.  All this makes me wonder when a more affordable alternative is going to turn up.