FunPub have tweeted to say that they are almost completely sold out of boxsets now. There is still a couple days left for registering (with or without a boxset), and there is so few boxsets left that there shouldn't be any on the site after the convention.
They are quite happy with the estimate of units this year, even though a larger number of boxsets went to non-attendees than they had originally planned/hoped. (more sold to non-attendees obviously means less people at the convention who are statistically more likely to buy their at-show toys)