Hmmm...  I have been watching this sale as a sort of a race to see what Archive would sell out first.

Though there haven't been any they have gone out of stock, I did notice this morning that Flash Archive Vol. 1 is no longer 50% off.  Just like Batman World's Finest Vol. 1. 

I wonder if this is indeed a sign of low stock, and an impending sell out.

I also noticed that the prices for Flash Vol. 1 have increased on Amazon.com.  No longer available there for the $25.00 mark.  But there are still copies still available at InStockTrades for the 50% off price.   Probably want to pick this one up if you haven't already.  It is a fun read.