Can Let's Kill Krampus still be purchased?
It is possible, but you need to contact the developers for information.

Based on the last social media post I can find from the company. 


  Hi folks, sorry if you couldn't reach us by email, we closed our
  website and it was linked to our Gmail, so we're figuring out some
  kinks there. We are not planning new releases or production runs at
  this time, but we do have some stock of LKK still available; we'll
  post more details soon for anyone interested!


this post was made on facebook December 20, 2014, so they may have already sold out.

https://www.facebook.com/ThreeFatesGames/