You should probably contact which ever company it is that gave your wife that information. It doesn't really make sense, so maybe she misunderstood what they said. I don't know if you're going on a dive boat, in which case, it would make sense to for them to charge an extra fee for for a non-certified person to come along for the day. But if this is for a shore dive at the park, maybe the $25/dive is going toward a DM or something....have no idea.
BTW, most divers around here dive wet (7mm wetsuit plus a hood or hooded vest). Some people dive dry, especially those who go fairly deep for a long time multiple times a day, like on a dive boat.