In some embodiments, the present invention provides for a computer system which includes at least the following components: a plurality of computing devices associated with a plurality of users associated with a plurality of users; where each computing device of the plurality of computing devices is configured to: electronically receive software which, when being executed, cause such computing device to display a plurality of instances of a specifically programmed graphical user interface (GUI); where each instance of the GUI is configured to display a real-time updatable meeting information representative of a direct electronic proximity-based communication between at least two computing devices associated with at least two users who desire to meet at a particular location to engage in a transaction of at least one good, at least one service, or both, whose marketable value lasts for a period of 30 seconds to 60 minutes.