The seller uses a low starting price – which is a bit strange. But perhaps he got it cheap and is unsure about covers from Armenia. He describes the cover as very scarce, which indicates in my eyes that he thinks the cover is genuine.
The front side looks a bit unclean on the left side, but paper and handwriting look legit. It is addressed to Tiflis. I do not like the registration label – it is probably genuine itself, but looks like it was not part of the cover back then. The cancel is also a bit off.
The backside show several stamps and the Aleksandropol cancel is seen with he “b” character. This is not one of the usual types used then and when you look at the front side you see the “x” instead of an asterisk. I have seen that one! Here is a blog entry I made about that cancel.
The receiver cancel of Tiflis is probably genuine – at least the part not on the stamp. You can see how unclean the part is where it enters the stamp.
If that is not enough, the overprints are crude forgeries too. This “hollow” version of the 100 r HH overprint is really ugly.