On our team a lot of things are taken into consideration. Grades play the most important part, fail or failing any class means no traveling. Also the more fundraising you did the better chance you have of going. Everyone has separate accounts for the amount of fundraising they did. We deduct the fundraising from the cost of going, some have to pay the difference. I don't know off hand how many students/adults are going this year but we try to take as many as possible. It also comes down to who wants to go and for the adults those that take the time off from work.
As a side note I've never gone to Nats with my team and only gone to two competitions in the six years on the team. I hate planes. I know one of these days my team will knock me out like Mr T and drag me on the plane or just lock me in the crate.
So you may just get a chance to meet me at Nats someday.