What are the different price tiers for download on music stores?

For iTunes:

Front: Tracks are around $0.99-$1.29. Albums are around $11.99-$12.99.

Mid: Tracks are around $0.99. Albums are around $9.99-$10.99.

Back: Tracks are around $0.69. Albums are around $7.99-$8.99.

Note: The album pricing cannot exceed the total price of the combined tracks.