I’ve been really into projected Halloween decorations the last couple of years. I hang a sheer curtains in the street facing windows. I project videos of ghostly apparitions on them. Atmosfx has some good collections that would complement a Lovecraftian creepy old house. They sell for $40-$50 per collection and are 100% worth it.
If you happen to have a projector, a sheer curtain, and know how to find video files from less than reputable sources… You can don’t have to spend any money at all.
Even the David S. Pumpkins Halloween Special?