Pixar Up 4 Disc Combo Pack with Digital Copy and DVD (Blu-ray) for $19.99.  Here is a screenshot for your reference.  Shipping is free on orders over $25.  If needed, use this Filler Tool to pad the order to qualify for free shipping.  One of the user reviews contains detailed description about each of the 4 discs.  At the time of this post, it can still be delivered before Christmas using Standard Shipping.  Alternatively, getting both Up (Blu-ray) and Monsters, Inc. (Blu-ray) for a total of $30.48 shipped as shown in this screenshot.

This post has been revised.