Mirror Maths

Here's something strange:

Order your copy of the Daily Mirror for £3.15 and get the new Prince album 20TEN for Free.

The Mirror costs, what? 40p. Postage can't costs more than a pound, even if it's in an envelope. And that envelope can't be more than 50 pence worth.

So how does paying £3.15 for a 40p newspaper make the Prince album "free"?

It looks rather as if the Mirror is selling the Prince album for £3.15 from where I'm sitting.