I feel your pain! We travel, with our two teens and often bring my folks or a niece along on our trips...it's not unusual for us to spend 5-10 k pp for everything ( depending on where we go), when you scale that up over a bunch of people the numbers are scary! And airfares are out of sight right now!
We went on a
ABD Costa Rica in 2007 and they were offering a deal for kids free in the room with adults- that was an incredible deal, because June in CR is a little bit " off season" , and they were still trying to build the new brand a bit. I haven't seen anything like that in a while now
Here are a couple of opinions:
-You can save a little with those agencies that offer a gift card or early booking bonus, it is small potatoes, but it does help!
-if it's a unique trip, you can save by pulling the kids out of school. We ( almost) did this for Africa. The price before July 1 was literally 1/2 price compared to after July 1. ( not ABD) I planned a 2 week trip, factoring no snow days ( almost unheard of in NE) before July 1 knowing my high schooler might miss a final exam...but I figured if the teachers didn't think this was a valuable educational experience they were out of whack! Luckily, it turned out to be the only year we got absolutely no snow days. Schools ended, we left the next day and got our 1/2 price trip
-Think of the value added and compare apples to apples. We've done lots of trips with different companies, and I've usually found that a very good fully guided trip with lodging on par with what ABD offers are priced pretty competitively.
When researching Africa, we found some real low ball prices. When I investigated I learned we'd be going overland ( takes days) rather than internal flights, some of the transportation was billed as " local". That's great and very authentic, but road transport is one of the riskiest things in traveling in developing countries, and I couldn't chance it with 3 kids. We didn't take and ABD to Africa, just because we wanted a different itinerary, but the trip we took compared favorably with it and cost us a bit more than the ABD, because we had more safari camp nights.
I know K&L isn't developing

, but the apples you compare there is the unique access ( without lines) you get with ABD, vs the cheaper options.
In the end only you know what's best for your family...I do hope you find the trip that works for you!