Our local kids rec league runs annual background checks on all coaches and assistants. We have an attorney on our Board and his office is able to use a service for this that costs us less than $5 per check. We've been doing this for the past few years and, fortunately, we've never had a problem. The obvious reason we do this is to protect our kids, but we also get a break on our association insurance.
I would strongly advise any of you who are associated with a kids sports organization to get them to do the same.