Manual T5 (V8) tranny's can be hard to find - can expect to pay anything up to $2.5k for a good rebuilt one (try talking to mal wood auto about sourcing one - www.malwoodauto.com.au
Unless your otherwise lucky, I'd guess your probably going to need to go to a wreckers. http://www.allpanelsandparts.com.au/
have a fair bit of gear. I know they had a V8 box a month back, and probably have a motor / loom as well. Actually, in their "new arrivals" section, I see a picture of a V8 donk, with the upper intake having a GT badge . . . could be interesting :) Look like its an ED....
You should have a quick search in the market section as well. While the ads expire in 30 days now, it wasn't long ago there was a V8 motor or two in there (can't remember pricing tho
Ohhh . . just had a closer look at one of the pics of that ED . . . the engine might be damaged - looks like there are some bit sitting at odd angles