Bitmain has now raised the limit to 5 per user:
Dear subscriber,
We have received a very promising response to the Antminer E3 batch. Thank you for that.
Many of our buyers have been unhappy about the limit of one miner per user that we had set to prevent hoarding and to allow more individuals to purchase this limited stock of the Antminer E3.
To allow all individuals to buy more units and, at the same time, prevent hoarding, we have now increased the limit to five miners per user.