I started a robotics club at school last year (10 sixth graders) and we competed (not so successfully) in the 2011 Food Factor challenge. We learned a lot from the experience though, and interest at school is extremely high. I am expanding the club to include this year's 4th and 5th graders so that they are familiar with things next year and so that the 6th graders (who will be a a different school next year) can help train the newcomers. I will probably try to use some of them as mentors or figure out a way to allow them to remain on the team.
My first concern is robot kits. We only have one Mindstorm Kit, but I suspect we will have enough students to have at least 3 teams next year. Do I need to get a Mindstorm 2.0 kit for each team or should I buy one more, then just add another brick. Money is somewhat of an issue, but I want to see what other clubs with multiple teams do. I assume that whatever I do, I should purchase things through Amazon.com or eBay.