I thought One Shot Tactical got all the AXTS stuff from Rainier Arms, (Rainier carries the Raptor charging handle) so it may be worth a shot.... Honestly it's going to be a one-off import through, and you're gonna pay a huge fee to get it in.
Knights Armament, Alberta Tactical and the Rainier Arms (as well as a bunch of others) all make ambi lowers, so it may be beneficial to get something a little more available... (Spikes Tactical has a really nice one too, so CTC supplies, or Questar may be able to get it?)
Although the AXTS lower does look very nice.