This is a great idea but can it really work? How do you deal with security issues, lost items? I think your solution create more problem than solving it unless you are going to prove me wrong? I have a simple question, If i connect with someone to help ship my stuff, and it gets lost, who will bear the cost?
The traveler will buy items from you, and sell it for the receiver. If the traveler lost a items in the trip, it mean he lost his payment.