The hard-costs are substantial for a print magazine (with a 20-song promotional music CD with every issue), but I bet it ends up working out well for them. I would have probably never subscribed without this promo (in fact I had never heard of the pub before), but now have thrown $5 their way to see what it's all about.
Paste Magazine :: Name Your Own Price: "For a limited time, name your own price for a one-year subscription to Paste. Yes, it's up to you. What's it worth to have a great read and a great listen delivered to your door every month? 11 issues and 11 CDs (roughly 220 songs) covering the best in music, film and culture. On the newsstand, one year of Paste costs $65.45; one-year subscriptions are $19.95. In February, we will recognize those who pay the most (more than the subscription price) in the magazine—and we even made it easy for you to give gifts."
Check it out... don't cost nuthin' (well, $1 is the minimum - but that's almost free).