"Since launching them we have reflected on the overall impact R4 cards will have on long-term software sales and I have talked openly to senior people at Nintendo UK about the situation," explained SimplyGames' Neil Muspratt, who we're guessing may have received a grouchy phone call from Nintendo. "We have concluded that they are not at all healthy for software sales."
Muspratt then urged Amazon to follow SimplyGames' example. As we write this, the R4 listing on Amazon's UK site notes that "we don't know when or if this item will be back in stock," though no official statement has been released by the site. As for all you UK-based homebrewers out there, just be thankful there are plenty of alternatives out there.