Of course I don't know if you're looking for specific issues or specific subjects only, new or back issues, etc., etc. Abebooks, sometimes Amazon and US and Canadian E-Bay carry back issues, but to avoid the European and Asian postal fees (which I agree have become exorbitant) you just have to dig the seller's location out in each case. I don't know of an easier way.
Search URLs on Abebooks for Armes and Gazette des Uniformes - some of these sellers are in the US.
I also like Combatbooks.com in St. Louis. https://www.combatbooks.com/aboutcb/?sectionid=1
I seem to recall they were considering carrying Armes Militaria, but I may be wrong. Lots and lots of uniform related books on this site.
What subject(s) are you looking for?
I have culled numerous WWI articles from Armes, Gazette des Uniformes, Uniformes and other magazines, but have little on WW2 or other conflicts. Nothing on Napoleonics. Will gladly share with anybody on the forum via e-mail. I've posted some reference info in the References section from time to time also.