Everything that is part of the promotion is supposed to be 1/3rd off, but if you hunt around a bit, or in my case just scanned through my extensive wishlist, you might find some things at an even deeper discount. There were a couple of items, mostly digital maps and some tokens that I found at 2/3 off!
Just a small plug for DriveThruRPG and judicious use of their wishlist feature. It really helps to squirrel things away there to look at later. From a publisher side of things I know your could (I assume they still can) reach out to folks who had your products wish-listed and send them a discount code to help convert them from shoppers to buyers.
...and for you "purists" out there notice it is GM's Day, not DM's Day! ;)