In this work, we demonstrate the design and implementation of a novel system called Async, which enables a mobile network operator (MNO) to efficiently manage the growth of mobile data. For this, we enable an opportunistic delivery model for the MNOs by leveraging the delay-elastic nature of certain applications such as video downloads, and the price-sensitive nature of certain users. Specifically, in Async, we enable an alternate content delivery paradigm that facilitates an MNO to control when, and at what price, the content is delivered to the users. In our system, users can select a price and expected delivery time (or EDT) option from a multitude of choices. We develop a prototype of such a system by extending Apache's mod_proxy module and by developing a service on the Android platform without requiring any modifications to existing network infrastructure or protocols. We demonstrate two applications using such a service: (1) download of large files, e.g., software updates, movie files, and (2) an educational App that downloads educational content on mobile devices.