can i put any sort of wood into my tank as long as its
well dried out / dead
and clean thoroughly..?

b/c driftwood at my lfs cost way to much and i want
a big piece !!

Yes.

Use something like Oak, Cherry or Apple. (Other hardwoods may work too so long as they're not toxic) Pine, Maple, Willow and Cedar are all bad choices. Cedar is hardwood but has nasty oils that will kill your fish, and any moths in the area.

Then yer gonna need to prep the wood. Cut off any rot, make sure it isn't infested with bugs or has any soft spots. Then scrape off all the bark. Wire brush, dremel or dremel with a wire brush attachment. Then take the wood, toss it into a rubbermaid tote, and fill it with water and a great big handful of salt.

Put a lid on it and leave it sit for a week or so. The salt will kill of most any microbes or any other microscopic funk in it.

The wood water is more than likely brown by this point from the tannins. Dump it out and add fresh water. Check again the next day, keep changing the water until the water doesn't turn brown anymore and it stays down without the rocks.

Then time to completely sterilize. You're gonna need a big pot, and it will be stinky, but boiling the hunk of wood will make sure everything is dead on it. You can bake it too, (185-200 degrees I would guess,) but there is a chance of it catching fire. If you have access to a kiln I think that would lessen the fire hazard, but am not sure on that.

Then yay. You have homemade driftwood that you can use in your tank.

Wow I didn't know it took that long...

yeah ok thnx erm since im from australia can you giv me any pictures on what too look for ?

i have alot of eucliptis and pine around but apart fromthat yeah ...

and the piece of wood is going to be big i guess !

aah no on the eucalyptus that will kill anything in your tank because of the oils it has no pine either, sorry I don't live around there not sure what you would use, maybe almond or acacia if you guys have them there?
good luck! I think the hardest part about curing big pieces is boiling them. you need a biiiiiiig soup pot!

You could do it on a grill too outside I think, also you could more than likely get away with skipping the boiling stage. With a week salt bath, at a high enough concentration ain't much gonna live.

You could also try wrapping it in aluminum foil if you go the oven route. I forgot that's how a friend of mine makes drawing charcoal.

As far as hardwood trees in Australia I have no idea. I know Pine is no good since it's a softwood.

My one plant book says you have Oak, Cherry and Sandalwood native. I don't know anything about Sandalwood but both Oak and Cherry are cool. Eucalyptus, besides the oil issue (that I knew nothing about) is listed as a fast grower. Most fast growing trees are softwood and won't make good driftwood at all.