Autumn is my absolute favorite season...and Halloween (Samhain) is my favorite holiday-for both religious and fun reasons.

My birthday is October 30th, and my anniversary is the 23rd. We even had an autumn themed wedding.
~Autumn scented candles: gingerbread, pumpkin pie, apple cinnamon
~Candy: If you need to go for cheap-avoid the popular chocolate varieties. Go for Smarties, Dum Dum or other sorts of lollipops, Tootsie roll midgies, etc. They are much cheaper per treat than Reese cups, etc.
~Other autumn decor items:
Mums for outdoor flowers, your table or something decorated with the tiny small pumpkins and gourds, Indian corn used as table decor or hanging decor, beautiful wreaths made of autumn flowers, leaves, berries, etc.
There are tons of beautiful decorations available in rust, orange, red, gold, etc. All of those things are nice for a general autumn theme, and can be left up through Thanksgiving.
If you want to go more "Halloween" you can add the fun things-the things with all of the Jack O Lanterns, ghosts, witches, etc. on them. In my 1/2 bathroom (guest bath) I have black cabinetry in there. I just bought a container of Softsoap that is black, with white ghosts all over it...and I bought a black hand towel with ghosts as well. It matches my bathroom, but also looks seasonal and cute.