The thing with the Jambos is I could sort of understand it in a place like Moab with countless trails in every direction you go. I could also understand it due to the difficulty of many of the trails.
However, you can hit all the trails on Drummond in two days of easy care free wheeling. They are rougher, but there is nothing there that would stop and mildly built rig except for a few deep water holes. Therefore, I don't see the need to spend that kind of coin to wheel there.
Events like DOA, or Snofari in West Branch, are like $50ish a person, which still isn't exactly cheap considering you're wheeling on public land, but you get to wheel with large groups of people, meet new friends, have an awesome banquet, and have the chance to win some cool swag so it's worth it. Especially if you don't know they area. However, I know Drummond Island very well, yet I still partake in DOA because atmosphere provided at big wheeling events. They provide entertainment beyond just wheeling. Then again, I wouldn't pay the kind of money the Jambo costs to be part of it either.
Support the sport. GLFWDA.org