Summer programs are pretty easy to put together. We're starting ours soon (a 2-week long camp) centered around one of the projects available here:
http://www.madlab.org/kits.html
It's understandable to be concerned about the cost of taking people to competition, especially when you're flying overseas. We started thinking about this after this past year, but for us the issue wasn't cost - it's what the less enthusiastic members can provide at competition and how it reflects on the team. It simply doesn't reflect well to have someone talking to a judge, the public, or other teams about our robot if they don't know what they're talking about - and you can't just sit them down and teach them everything in a few hours.
So, we're looking at having attendance requirements. We haven't set anything in stone yet, but it makes sense that only the most dedicated people (90%+ attendance) be allowed to be in the pits and interacting with the judges and other teams. Those are the people who are going to know whats going on. Likewise, going to competition is something of a privilege (missing class, going on a trip with your friends, etc). If you don't show at least moderate dedication to the team (like 50%+ attendance), then you don't get to travel with the team.
The key to keep everyone satisfied with the team is to be upfront, and give them a chance to participate in the decision process. If everyone knows before the season starts that they can't travel with the team if they don't attend enough, then the only one they have to blame if that happens is themselves.