yea $39 for an A3 upper is a great price i got one a while back when they were $49 --recently ordered two more.
don't know when the sale will end as they have sold out of them before and a few days later the blem uppers are back in stock. they may have 100,000 in a warehouse somewhere --then this could be the last of them--ya never know.
last time i checked they had about 800 in stock and they seem to be selling about 200 a day so there are enough for a few more days if the don't pull the sale price for some other reason--
PSA has been my go to AR place lately--