Have you looked at the financials of this? 10$ for 1 hr delivery means that either the carrier is paid less than that hourly(and I guess at least 20% less than that) or he is supposed to deliver more than 1 package per hour. Considering transportation costs and idle time, I am not sure this will work smoothly. It will work if there is a list of carriers ready to drop what they are doing to go buy groceries and make some money. Basically, it will work in cities with lots and lots of students...