Calgary Shooting Centre offers GSCI night vision. While I would personally recommend you go with something a bit higher end such as ActinBlack, GSCI is certainly decent quality. If you want ActinBlack, they are excellent to deal with directly.
From ActinBlack, you will be waiting a bit for shipping/clearing customs from Luxembourg. GSCI from Calgary Shooting looks like about a 2-3 week lead time, so you will get them quicker.
Gen 3 from either are going to be quite expensive. Gen 2+ Photonis Echo tubes will be quite a bit less money than the Gen 3/XR5/4G. Photonis Echo tubes do offer good specs for the money, in my mind, since we can't get any US Gen 3.