There's a whole thread here for people who want to share specialty cruises during Illuminations and Wishes fireworks shows. The boats hold 8-10 people and most of the time traveling parties are smaller than that, so they share the cost and the boat with another family going to Disney at the same time.
A little risky, sharing cost and a boat with strangers, but the worst thing that can happen is your parents get the boat to themselves, and you pay full price ($260-$300).
That's what I'm doing for my parents as a Christmas present, anyway. They're going on a Holiday fireworks (Wishes, but in Dec) cruise and I'm trying to include some other families.
