For limited time, Adorama has the Rokinon 14mm F/2.8 Lens for Canon available for 249$. Please see other mounts for discounts as well. This is an excellent lens for Astrophotography. The lowest price that I have seen on SlickDeals is around 225$ on Amazon Lightning deal for Prime Users. But Adorama has no tax for most of us, so this deal comes pretty close.
Alternatively, B&H has the same deal as well.
B&H allows you to build a bundle with Adobe Creative Cloud Photography Plan to save an additional 20$. I called Adorama but unfortunately they do not offer the 20$ discount on the Adobe Bundle.