In the wake of NVIDIA announcing the 'Turing' GTX 1660 Ti GPU, AMD announced a limited period offer for the Vega 56 by bringing down the price of the card to the same US$279 price point. Unfortunately, though, the card appears to have been sold out and it is not known if and when AMD will reinstate the offer again.
https://www.notebookcheck.net/AMD-briefly-drops-Vega-56-to-US-279-to-take-on-the-GTX-1660-Ti-sells-out-within-hours.410646.0.html