2. A really great costume for next year. This is the time to buy masks and good quality costumes. They are usually on sale and if you aren't tied to buying your costume right before Halloween it can be a great score.
3. Animatronic yard decorations. They go fast (like the first few days after Halloween fast) but you can find some great deals!
4. Good quality fake pumpkins. There are different quality fake pumpkins and without a doubt the expensive ones are better. They don't have obvious seams, they have better color and are thicker so they look more authentic when carved. In general faux pumpkins are great because you can carve them and put them out really early or leave them whole and have them out until Thanksgiving without getting rotten pumpkin on your stoop. I always mix fake and real pumpkins together it makes the fake ones look better.
5. Fog Machines and Fog Juice. You can get a great deal and fog juice will last you practically forever so don't worry about storing it. One piece of advise- check the machine this year to be sure it works then clean it out and store it. Good fog machines are more expensive then anyone (including me) would buy for their home so anything you find in a store (even if it's expensive) is pretty much considered a cheap fog machine so make sure it works while you can still return it.