Many times a person has some service or material item to offer in exchange for something they desire but the other person doesn't need that service or item in exchange. This is why it is beneficial to establish a college bartering bank.
In the simplest case: Person S wants to take a class from X, and deposits a bike in the bank that X does not need. Person T wants to take a course from Y and deposits plumbing services in the bank that Y doesn't need. S takes the course, T takes the course. X needs plumbing work that T offered done and makes the withdrawal. Y needs (conveniently) the bicycle that S offered and makes a withdrawal.
This system does not exist yet, but we can work in that direction. It will facilitate non-monetary exchange.