I always try to buy things that I can use more than one way. I pick items that involve solid colors, especially neutral ones, and clear glass. That way, you can use them more than just once a year, or for one specific holiday. I've used the white candles, the clear vintage bottles, and the brown bottles several different ways. (The brown ones are recycled beer bottles. Anj bought them one weekend, and I thought they had a unique shape, so I kept them and soaked them to get the labels off. The owls were ugly when I bought them, but I spray painted them white, and I think with the right mix, they can look sort of eerie, but can also work well with winter decor involving lots of other white, black, gold and silver. Same with the black birds. They can look creepy with the right mix, but look totally happy and cheery with something else. Also, with the jack-o-lantern banner, I flip it to the other, plain pumpkin side for before Halloween when fall first arrives, and again after Halloween when it's time for Thanksgiving.)
If you can find a color theme to stick to for your holiday decor, you can always make things stretch a lot further by using random glass, vases, candles, etc that match as fillers when you just need a little more oomph.
I also think that a mantel looks a zillion times better if you can find a way to create some height. That wire basket has been used several different ways as well. It adds some texture, but it's a neutral color and can be mixed with a lot.
Do you decorate for Halloween?