"OMG".Look on eBay,or other websites,for Official Police stocks.You can even use the plastic or "Coltwood" that originated on the W.W. II Commando,a parkerized O.Police. Those are the "smaller style" you are seeking. Don't have to get a mint pair,so my guess would be around $25. I have a couple of pair,but they would be "pricey",
Glad that you are teaching the youngsters,and the O.M. is a "great teacher". You also might want to consider fitting a Pachmayer or Tyler grip adapter,for those smaller hands to better reach the trigger.
Good Luck,and thanks for teaching them the right way at a young age!