Yes, convention registration is for the entire convention. This is by design. It is extremely affordable, and is intended to encourage you, your spouse, and your teens to participate throughout the entire convention.
You will not find a more affordable Homeschool Convention anywhere in the United States! It is conceivable that you might find a marginally “cheaper” convention somewhere, but it won’t be a convention that provides the same Exhibit Hall selection, seminar & workshop variety, outstanding speaker roster, Real Faith for the Real World Teen Track, and more that are available to you when you attend a Great Homeschool Convention.