Apple - I just bought the wrong album on iTunes. How do I give it back?

http://www.apple.com/support/itunes/

Contact customer support via e-mail and hopefully you can get a refund.

You can dispute the purchase within iTunes.

• Go to iTunes Store, view your Account (login if needed).
• Find and click on Purchase History.
• Click on the arrow next to the purchase to see the details
• Click on the report a Problem Button
• Click on the Report a Problem link next to the Playlist/Album in question.
• Select the Problem from the dropdown ( I inadvertently purchased this playlist)
• Fill in any comments.
• Hit Submit

This will send the request off to Apple Customer Support and they should credit you back. I have not done this myself, but a co-worker has and said it worked fine. They will likely flag your account though if this becomes a common thing.