[Dale]

Both Vex and FLL are good options. Part of your decision might be what is most popular in your area. You don't want to travel far to a competition. I've been leading FLL teams for the last 13 years so most of what I'll say is from that perspective.

The experience of students will vary greatly depending on the coaches and teammates. You are right to focus on finding the right people. It's more than just are they willing to run the program at a school but will they give the right amount of organization and mentoring. You want to hit that Golilocks zone of not mentoring too little or too much.

All of the FLL teams (3-5 per year) our FRC team runs are coached by the FRC students. I'm the adult overseeing those high school coaches but the student coaches handle all the day to day activities of their FLL teams. Those teams meet twice a week in the fall for 1.7 hours per day. This is great for the younger kids but also great leadership training for the high school students.

Our rule in the Lego lab is that coaches never touch the robot nor the keyboard. They are there to keep the students on task and lead brainstorming sessions. They ask probing questions, not deliver answers.

If running the teams with your high school students isn't practical, focus on finding adults who are good with kids. That could be teachers but is just as likely to be parents. Many teachers these days are over-worked and are reluctant to add one more thing. The most important point is that the kids have fun. FLL can be a great experience but it can also be worse than not doing it at all with the wrong coach or team. A lot depends on the coach and making sure the kids who are in it really want to be there.

Financially, we usually charge the parents a fee to cover expenses and then have scholarships for those who can't afford it. That would depend on the demographics in your area. No matter what it will be cheaper than daycare.

There will be a significant up front expense buying Lego or Vex parts. You'll have Lego parts and FIRST registration / field kits for each FLL team. FLL costs a minimum of $800 per team the first year. It's less from that point on because you'll have the Lego kits. In my opinion a single kit is good up to about four kids per team. You'll wish you had another Lego kit even at four students but bigger than that it gets very important because there won't be enough for everyone to do otherwise. The software kids will be constantly waiting for the mechanical kids who are waiting for the software kids. In any event don't let FLL teams get bigger than 6 members. FIRST will let you have 10 kids on a FLL team but there really isn't enough for them to do. Much boredom and distraction will ensue.

The way we run FLL, with a light coaching touch, means that we start it in 6th grade. Younger students do FLL all the time but developmentally they will need a lot more handholding. That can easily lead to coach over-involvement. You'll see teams of fourth graders at FLL tournaments with robots that look like a Lego master builder constructed them. That means some well-meaning adult got sucked in and was overly involved. Maybe the judges will catch it and maybe not.

If you have other questions, let me know.