So, it seems that there are no Nexys4DDR boards in stock in the USA, UK or continental Europe.
We probably aren't the major cause of this, but it would be funny to find if we were.
For those desperate in the meantime, it might be possible to get them from the Australian distributor, although where I am at the moment it isn't trivial for me to find out their stock levels. Perhaps someone can leave a comment with what they find out.
Otherwise, Digilent seem to have another production run scheduled for later this month, with stock shipping again from the 29th.