It says its $6.66 (heh) But I see no buying option other than this bundle which has Nun Massacre in it and I already own that :/
Yes, you can. $6.66 is the price of just this collection with Feed Me Billy, Night Shift, Spiders and The Riverside Incident.
The bundle with Nun Massacre is actually here: https://itch.io/s/19798/halloween-puppet-combo-bundle