Everyone does a scavenger hunt from time to time.  You've probably done everything from back to school to video or clue-based scavenger hunts.  Next time, take a moment earlier in the week to call your local mission organization and ask them what supplies they need.  Then, use those items (all new unless the mission will take used) for your list.  You decide on how many points each it worth, and voila!  Your scavenger hunt will be more than just a good time for your students, it will harness their connections and resources to help fulfill the needs of your community.