Haka House is a hostel, and I know you might be used to more luxurious accommodations (like myself!) but there is very little choice in Mount Cook National Park and it's soooo expensive!

If you book at Haka House in advance you can score a private room and feel like you're in a hotel anyway!

If you must have nicer accommodation (fair enough) and don't mind paying out the nose for it then the Hermitage is a very popular option.