You can now buy the There Swings a Skull: Grim Tidings soundtrack on Steam! It can be found here:
https://store.steampowered.com/app/2145730/There_Swings_a_Skull_Grim_Tidings_Soundtrack/
There Swings a Skull: Grim Tidings OST is now available!
Source: Steam Community (opens in a new tab)