Just from how I've seen box passes work:
The owner of the pass would put whatever they wanted to start into the box and create an inventory list that would be posted in the thread. You could put in a range of items between $1-$50 if you felt inclined.
The first and future recipients of the box would then select which items they wanted and replace with item of reasonable value (or you could do with like item). The recipients would post what they took and what they replaced it with for approval by the owner. This enables the owner to call b.s. if
someone where to try to pull one over on the box pass owner.
The box would then make it's way through the list of people that had signed up ahead of time and eventually making it's way back to the owner where he or she should receive a box of new items that were not started in the pass.
I think it is a great idea with a few questions... 1) all items placed in the box would be new and unused, correct? 2) If they are not new, how do you determine value?
I'm in, if you can get the logistics worked out