At http://www.emusic.com/me, sign up for a free trial subscription (credit card needed) and get 50 free MP3s and, optionally, 1 free audiobook, from a wide selection (including many new selections). Quit during the trial period (30 days for the music; 2 weeks for the audiobook) and avoid any charge; otherwise, you are continued with your monthly subscription, getting tunes/books each month (for your monthly fee) under the program you’re signed up under.
Although a credit card is needed, it is simple to quit the program during the trial program, without any issue. And the program works well, as long as no non-normal issue develops (customer service can be nonexistent).
Just a thought, and offer.