The Drobo 5C was introduced in October 2016 for $349. There has already been a $50 discount code ($299) and a one-day Amazon.com sale (also $299). Yesterday, the price tracking site, Camel Camel Camel, alerted me of a $279 price on Amazon:
By the time you see this posting, the price may no longer be valid, but you might consider activating a Camel Camel Camel account to do your own tracking. You will receive an e-mail alert when the desired item (anything on Amazon) reaches the price you want. It also shows a historic graph of the price the item has been since tracking began.