Follow tinkamom's directions. The offer is there but no way to book it online. It directs you to call Disney or a TA to book.
Tinkamom, the site actually says that the $435 per adult price is based on two adults in a room, etc. Like all other Disney packages, this one is flexible. If you scroll further down the page, there is also the "Children 3-9 must choose from Children's Menu, if available" disclaimer.