peter11, you've started a fun thread, but I'm still not sure what you're really asking about. Are you thinking about starting your own liveaboard company, or reselling liveaboard trips (like a travel agent)?
We've never been on a liveaboard, but we'd like to do a liveaboard once per year. It's just hard for us because we have young children, so we'd have to ask Grandma and Grandpa to watch the kids for a week or more to do that. More often, we go on trips with the kids where we can get excellent childcare for them on-site for a few days. We go diving in the mornings while the kids are in childcare, and spend the afternoons/evenings with the kids. Disney's Aulani resort in Hawaii is one example of a place with great diving and great childcare; cruises (like Disney Cruise Line, Carnival, Royal Caribbean, etc.) are another example. We go on about 2 week-long trips per year like that, and we'll usually get in 3 2-tank boat dives in a week (6 dives total). We'll spend about $5000-6000 for a family of 4, with 2 divers, for one of those trips.
We also take a weekend trip to North Carolina or Florida a couple of times per year. Sometimes we bring the kids along and Grandma and Grandpa take them to the beach while we dive; sometimes we leave the kids at home with their grandparents for the weekend. Those trips are closer to $500 per day for a family of 4, of which half is diving expenses for 2 divers, with one 2-tank boat dive per day.
Sometimes we'll sneak in a dive in an aquarium while we're on another trip. We've done that twice, and would happily do it again. That's about $175 per person. The kids will visit the aquarium with Grandma and Grandpa while we do that, and they can see us in the tank when it's our turn.
The rest of our diving (about 1/3 of it) is local quarry diving. About half of our quarry diving is taking scuba classes, and the other half is just for fun. Classes usually cost about $100 for a daylong class, while just diving for fun only costs about $10 per tank for the air fills.
We get in about 20-25 dives per year, and we own most of our own gear. We just rent tanks, and if we're travelling, we'll rent weights too. We occasionally rent other things like wetsuits if we're trying to travel light.
We've always booked our own travel, but we have seriously considered taking trips sponsored by our local dive shops. They set up group trips on liveaboards and group trips to popular diving destinations like Bonaire or the Florida Springs.