I LOVE the Dollar Store for haunted house type things!!!
Some ideas I have off hand would be voodoo lanterns. I buy the 3 pack of LED tealights and grunge them up and put them in a jar (glass or plastic) that's grunged up with a little moss or ash or dirt in the bottom. Add some twine and voila! These can hang from anywhere and you can also get the twine from $1 store.
Also the cheap grow in water critters look great in jars as well. You can make specimen labels on your computer, grunge the paper up before you send them through unless your ink is water permanent or use a copier to make a copy and you can grunge over copies. You can make tags, labels, etc this way for a whole apothecary full of bottles and such.
Allen has a ton of awesome Youtube videos on using $1 store finds. You can find him under Stiltbeast Studios. He makes fake blood, corpses bones, and lots of good stuff!
If there's something specific you are hunting for, I might be able to help with a low cost solution. I love cheap stuff.
I also included a pic of my Venus Fly Trap plant, which was essentially made for free minus the plastic urn it sits in and some cans of $1 spray paint. It's all lightweight cereal box style cardboard and newspaper. And Model Magic for the teeth. plant 1.jpgplant3.jpgswamp lantern oc.jpg