Deviled eggs topped with creepy crawlers. There a lot of deviled egg recipes in the internet that you can use but the simple trick here is to source spider jellies to bring out Halloween feel.
My colleague who runs a small catering business on the side sells coffee jelly in shot glasses. They are always a big hit in our office parties so we decided to add this to our Halloween menu and just put worm jellies to "spice it up".
Another easy peasy finger food is quail eggs. Just add a drop or two of red food coloring and you now have pierced eye-balls in your party spread.
Grilled and barbequed food are always a big hit so why not leverage on that by adding grilled goodies with a twist (chicken feet, pig's blood, chicken intestines).
In any party, especially with limited budget, creativity is key.