I remember dressing up as a Gohostbuster for Halloween as a kid. I didn't have any official merchandise so I had to make everything.
For my proton pack I wore the family vacuum on my back attached to a camping pack frame. The hose out of the vaccum was attached to the end of my Star Wars Han Solo blaster pistol. I drew all the logos and nametags myself so you know they were top notch.
Today's halloween costumes are way too ready-made for my tastes. Kids hardly have to think at all.
I'm not dressing up for Halloween this year (I'm 30...it's just be wierd).