Amazon is having a special promotion linked to the Blu-ray release of
Alvin and the Chipmunks and
Alvin and the Chipmunks: The Squeakquel: if you buy both titles as part of the same order, a discount of $7 will be applied at checkout. There is no information as to when this offer will expire.
At the time of writing, this results in a total price of $26.48 for the two movies.