Bake sale idea

Remember that most bake sales involve kids so sometimes simple single serving treats are better sellers especially when they are homemade. Have you noticed how many people show up with a box of entenmans?

I love that idea of DIY kits.
There was a product I saw that might translate well to that; Just the filling for pecan pie in a jar that you mix eggs with and pour into a pie shell.

For the spice fiends. How about sriracha salt? It's 5tsp of siracha mixed with 1/2 cup kosher salt. Dried in the oven smashed back to salt--use as a finishing salt, Bloody Mary rim salt, salad, Popcorn etc. In a nice 1/2 cup caning jar, with a label and suggestions; those would sell well for 'hot heads' that love their spicy stuff.
http://food52.com/recipes/11404-sriracha-salt

Taking your s'mores idea in a far more simplistic fashion, what about s'mores Rice Krispie treats? Half Rice Krispies, Half Golden Grahams, topped with chopped milk or dark chocolate.

I would make these pumpkin butter bars by Paul Virant: http://citygardenlife.com/butternut-squash-savory-tart-pumpkin-butter-bars/ I actually haven't made the bars themselves, but I made the pumpkin butter and it is out of this world. I've also made no less than 11 other recipes from this one-Michelin-starred chef's cookbook; every one of them is outstanding. The pumpkin butter captures the flavors of pumpkin pie intensely and with the perfect formula of spices + dairy (real butter, that's all). I roasted the pumpkin butter in the oven, for a bit longer than suggested, which caramelized all the sugars resulting in rich toffee flavors as well. ;o)

I tend to not make anything with nuts. So many people are seriously allergic that I usually opt for nut-free goodies. Your s'more kit sounds fun, and you can always make it nut free.

Other things I've made for bake sales:
whoppie pies
oreo fudge
cherry cheesecake cookies
mint brownies
hot chocolate on a stick