If you bought into Columbia House in the 90s, as I did, the math worked out to ~$10 average for each CD over a year (the 8-for-a-penny plus the full-price ones), back when they were $16 each at the local store.
The promotional offer was an attention-catcher, but you still saved $4-6 per CD.
Just because you feel like "there must be a trick" doesn't mean there is a trick.
