Starting a FLL program

[k4r3n2]

My team is interested in starting up an FLL program at our local middle schools, but we're concerned about the cost factor in registering teams. We don't have enough money to afford to pay the registration fee for all of the kids that may want to be involved, nor do we want to pay $600 to sign up kids that aren't really interested. We have had some ideas to gauge the interest of the kids, such as hosting a mini-tournament sometime during the beginning of the school year where the winners get to join an FLL team paid for by our sponsors, but I was wondering how your teams deal with paying for the kids, making sure they're interested etc. etc.