Just yesterday, Apple has quietly removed the last non-retina display original iPad mini from both their website and the physical Apple Stores.
It was about time though. The original iPad mini was first released in 2012, but it was still being sold along side the two new successors for a reduced price of $249 for the 16GB variant.
This device is the last iOS device Apple still sold without their famous Retina Display. It has a resolution of 1024 x 768 or 163 ppi. It is also the last iPad with a 32-bit architecture in the operating systems, this means that developers should be confident on working across available devices.
Of course, you can still buy refurbished devices in other stores, and resellers will still have some stock left in their inventory, soon the device will phase out.