Cosmic Horror Sale is a 25% off event for Mythos-type games (Call of Cthulhu being the prototypical example and 800 of the 2900 sale items are Chaosium products never mind CoC-compatible products).

The only things I found interesting and that I'll probably buy are

Goodman Games Gen Con 2016 Program Guide ($15 sale price) - for Metamorphosis Alpha material
Goodman Games Gen Con 2017 Program Guide ($9.75 sale price) - for completeness

Although now that I write it down they're really pricey considering what I'll end up (maybe) using, so then again maybe pass.

There are basically three good RPGs in the sale: Call of Cthulhu, Delta Green, Alien. If I had $50 I think I'd spend it on Alien since it's science fiction.

Alien RPG Core Rulebook ($18.75 sale price)
Colonial Marines Operations Manual ($15 sale price) - to run a military campaign

Three published adventures but they're linked so I don't particularly want to buy only one ($34 for 3 PDF scenarios...).