>8) Lastly, I'd vote that if the consensus is that an item can serve multiple people you ought to be able to pro-rate the cost and weight. Example, if two people can get by with an 8x10 tarp for a sleeping shelter I'd vote to count half the cost and weight.
This thread reminded me that I had been meaning to make a cheap plastic tarp. The first chapter in Ray Jardine's The Ray-Way Tarp Book describes the "poly-tarp", a 10x14 piece of 3-mil polyethylene plastic which was used to shelter four adults. The 3-mil plastic was also used for ground sheets. I think it will be tough to find a cheaper and lighter 4-scout shelter, which weighs about 9 oz./person at a cost of about $2/person (including guylines and stakes) and can be made by the scouts within a few minutes. Guylines can be made from Venetian blind cord, which costs about $2.50 for 50 ft. (enough for one tarp) and weighs about 1 oz. For tent stakes, thin steel or aluminum rod can be bought in bulk, cut to length, and bent in a vise; six stakes would cost about $2 and weigh less than 4 oz.
A single-person shelter could be made from Husky Contractor Clean-Up Bags, which are 4 ft. x 5.5 ft. (cut open) 3-mil poly. Two bags taped together with packing tape would probably hold reliably, yielding a 5.5 ft x 8 ft tarp weighing about 15 oz. for less than $7, including guylines and stakes.
As for stoves, most of the do-it-yourself alcohol can-stove designs involve sharp objects and tools. However, the SuperCat stove (the description is on BPL somewhere) involves nothing more than a cat food can and a hole punch (stove weight is 0.3 oz, and it acts as its own pot stand). Consider the Robinson Cat Stove for multi-person cooking. But probably the lightest stove+fuel solution, also easily made and promoting fire-building skills for scouts, is Ryan Faulkner's "1.5oz wood stove" (BPL thread). Cost of stove: free (tool required is hole punch, can punch or old scissors, which are household items).