I like lots of candles, LED if there's a chance of them being tipped over. Candelabra are great-- bigger the better. If you can find some at flea markets or on AU ebay, you might get a deal. Also if you have or can find a tall spindle you can transform a table candleabrum into a floor-standing one.
Draping fabric is good. Sometimes you can find tablecloths or satiny sheets on sale, and get the fabric cheaper per yard than you'd get at fabric store. I've never gone fabric shopping in Australia, but here in the US it tends to be pretty expensive.
You probably have at least a bathroom mirror, maybe more. Last Halloween I had an unsuccessful go at covering mirrored closet doors with a frosted plastic film (like Contact Paper, but not that brand) with a ghostly figure behind it, but in the past it has worked with smaller mirrors.
a_granger- thanks for that tip! I have it down on my Halloween "to do" document, along with your name to give you credit if I wind up posting pictures