The most elusive stamp in Volume 1, Syria 106c, has been offered twice to my knowledge this year. (My knowledge, unfortunately, being after the fact so I couldn't alert anyone.)
Cherrystone in July 2022 offered one copy as part of a lot that sold for $230 before fees:
Lot #1436
SYRIA
1921-22 selection
of seven inverted or double overprints, some duplication, including
25pi on 5fr, also "25c" on 10c green (error), h.r., fine-v.f.
Rasdale had a copy in their November auction that Big Blue blog's reader Ray was able to acquire for the bargain price of $120 before fees. You can read more about that by scrolling down to the bottom of Jim's blog entry for Syria:
https://bigblue1840-1940.blogspot.com/2016/04/ClassicalerastampsofSyria.html?lr=1
And check out the thread here:
https://www.stampcommunity.org/topic.asp?TOPIC_ID=82497&whichpage=1
I don't actively search for 106c these days, so any new sightings would be most appreciated. (Thanks Bud for the heads up about the Rasdale sale.)