According to this article 3 are available in the US. http://www.omgubuntu.co.uk/2015/09/do-you-plan-to-buy-an-ubuntu-phone However its not clear to me how to get one. What are the carrier options? Thanks.
BQ offers global shipping when ordering from their online shop:
But you should be aware of the compatibility to only two carriers at the moment, which you can read about here:
Meizu does not offer global shipping at the moment, as far as I know. At least there is no reference to a US reseller.