I think Rigging kits would be a cool addition. Kind of like the nut & bolt kits at the hardware store. Should have a small range of the really strong solid/split rings, hooks, swivels and possibly an instruction sheet for making leaders. Put it all in one of those compartmented plastic cases....and add in a decent pair of split ring pliers. A good way to get the new folks started.
Now all is needed is what most folks said...reasonably low priced strong lures.