You can pre-order the Big Hero 6 (Blu-ray + DVD + Digital HD) for $18.90 (list price of $39.99.)
This will be released on 2/24/15. They have a Pre-order Price Guarantee : if the Amazon.com price decreases between your order time and the end of the day of the release date, you’ll receive the lowest price.
Turn it into a fun family movie night at home!
Remember, prices flip fast so check the current price before ordering!