Understand the sticker shock but you may want to consider this...
The boat you quote the prices for includes an excellent breakfast, mid morning snack, catered lunch, and wine, beer, and champagne if you please. There are inwater guides for the snorkelers-they lead a tour, find and identify marine life for the snorkelers as well as ensure their safety. There are a handful of divers aboard with gear that is less than 1 year old and a very limited number to each dive group either 4 or 7 depending on which site you choose to book. That boat is made to hold 99 but is only booked to 60max so it truly lives up to it's hype. The amenities onboard more than make up for the price when you consider all you get. The inwater sites are selected specifically to meet the interests of both snorkelers and divers.
You can get a trip a little cheaper (still in the 150.00-175.00 range for divers and usually about 90.00-110.00 for snorkelers) with almost any SCUBA boat. However, that means that the boat will usually be moored in about 60 ft of water or more for the first dive and 40 to 50 for the second. Most SCUBA dive charters are also 5 hours long which accomodates the dive plans, movement between sites, and surface interval/gear prep for the divers. For the snorkelers this usually means 2 hours or less of in water time Also, this is usually in water too deep to enjoy the snorkeling. That can be a real drag for the snorkelers especially if it is a rough water day as the divers will be able to get under the surface conditions but the snorkelers will be subject to them on or off the boat. A boat with a combined agenda will find a sot with in the lee of the winds or waves as much as possible to make the experience good for both divers and snorkelers.
There are also other large boats that cater to snorkelers that will take along a few divers. They do cost less if this is your top priority. Their amenities are limited, they are booked near to their coast guard rated capacity, their crew to guest ratio is much less, meaning their in water support for snorkelers are crew members on kayaks for safety but no in water guidance. Diving is secondary, as they still go to the parts of the reef that they originally went to when they only catered to snorkelers. They provide basic food but nothing like the luxery sailing cat you have looked at. This is obviously still preferred by some and I am not meaning to belittle them, they have their place but be sure that you really want the bargain trip. Most of these will still be around $100.00 per snorkeler and $160.00 or so per diver. That kind of puts the other boat in perspective.
Yes, I work in the industry here and have been out with almost all of the boats at least once. Unless your snorkelers really enjoy deep sites and are very hardy when our trade winds start to blow, for their sake I would do one of two things. I would choose the luxery sailing cat if you only have one day to go or I would suggest the divers book a SCUBA charter on one day and join the snorkelers on a snorkel only trip out of the Kihei Boat ramp on another day. There are several 2-3 hour snorkel tours that would not take most of a say but still give you about 2 hours of snorkeling time. If you choose to go to a different destination on the SCUBA charter you are still bound to enjoy the snorkel charter as well.
Happy planning
