A simple plastic dollhouse can be painted and turned into a creepy Halloween house for your mantle!
Sometimes you can find these at Value Village for about  bucks.

There is a set of orange string lights glued onto the inside as well as lots of embellishments. Spider web, insects, skeletons, pumpkins etc etc....once the inside was done, the house was permanently glued shut and affixed to a wooden base.
Misc outdoor branches glued to the base to resemble trees. You could do anything to make it look like it's spooky. I like the spider web through the branches.

An extension cord to turn on the lights and voila!