Heat/cooking/container:
Hobo stove made from coffee can:
http://www.knifeforums.com/uploads/1247846380-hobo01-01.jpg

Firestarter:
Tinder: Petro jelly + cotton balls.

Polished soda can bottom for using solar power to light things on fire (doubles as a mirror):
http://www.wildwoodsurvival.com/survival/fire/cokeandchocolatebar/

Lastly take old used up lighters, cut them in half (or don't for safety's sake) and just use them for the flint striker.

You could also pick up a bulk pack of waterproof matches super cheap and split them for low cost per kid.

Tools
Rope/cordage - I agree about the fishing line; perfect choice.. or twine.

Tinfoil/Duct tape. Cheap - buy a big roll and give each kid a set amount.

Knife - razors or start teaching kids how to make their own.

Extra
Heavy duty ziplok bags for water storage/misc

Trash bag ponchos (try to find trash bags that are heavy duty and make sure you wash them to get rid of the pesticides they are coated with) make sure you use duct tape around the head/armholes to keep the bag from ripping.

Food: - have them each grab some salt, pepper, sugar, ketchup packets from mcdonalds next time mom brings them there.



That's all I've got, thanks for the interesting post.