Your local hobby shop (if you have one) has a bunch of modular parts for various RC airplanes. What is needed, I think, is a modular foam CL trainer, electric, which comes (quoting an ad here) "Everything you need in one box for an excellent trainer". Cost well under $100, probably under $50. Look at all the RC stuff out there that is as I have described. It should be an attractive airplane, not a profile. There should be available, hobby shop and on line, replacement parts. Also an upgrade kit which converts the trainer into a stunt-capable airplane.
As a source of kids, check and see if you have a local homeschooling association. For the kid to become a modeler, there has to be parental support. If you do it right, you may be able to hook both parents and kids. Home school parents are investing time and resources in their kids. They are also looking for socialization opportunities and are not locked into all the activities of the usual school kid. If you want to try a local school, go for the people in detention hall and in school suspension. The school may be glad for you to 'babysit' them a bit, and the kids may well be interested in doing something which normal kids don't do.