I made good on my promise to try out making S'mores from scratch (if you can call making something from three highly processed ingredients "from scratch), and this is how things worked out:
First off, the costs. I went to a somewhat overprice grocery store for the graham crackers and the marshmallows, which cost $3.99 and $1.29 respectively. Ironically, all of the available chocolate bars were too fancy for the purposes of re-creating a campfire dessert invented in the 1920s, so I had to go across the street to the British import candy store and get a genuine Cadbury milk chocolate bar. The shop is stocked right now with all sorts of imported Christmas treats (the Guinness pudding was very tempting but too expensive for me), so I wound up getting one of the big bars that they don't always have. This was the most expensive ingredient, at $5.99 for a 230g bar.
Including tax, that put my total investment at $12.84, which matches the kit, but I got larger amounts of the ingredients. Unless the kit came with pretty amazing North American chocolate (doubtful), I got better quality ingredients as well.
The graham cracker package conveniently had S'mores instructions on it (I just can't bring myself to call it a "recipe"). I followed them and had some ready in well under five minutes. A hint: if the marshmallows keep falling off the piece of chocolate (mine did), split them open a little to expose the sticky insides, then push them onto the chocolate a little. The inner part not covered in powdered sugar sticks like glue.
Now that I've tried them, I don't get what the fuss is all about. Then again, I'm a Rice Krispies squares fan, and I'm sure if I hadn't grown up with those I wouldn't get what that was about either. I suspect that S'mores taste better if you're in the middle of a mosquito-infested national park and have just had hot dogs and beans for dinner after hiking for hours and desperately trying to fill in your "identify local flora and fauna" assignment, even though you haven't seen a single hawk all day and all the plants look the same to you.
Given that wrapping paper is so cheap, I think that if you're going to give S'mores ingredients as a gift, it makes a lot more sense to self-assemble. If the person you're getting it for loves S'mores that much, they probably don't associate it with yuppie-style packaging.