I know of many places that can build them for you! Sydney a good mob to talk to is Noltec engineering Northside number 9980 9777.
In Melbourne Hot bits, I dont have a number but they are pretty helpful when I have spoken to them.
Sorry Mate it took me a little while to get a number, I have no idea what you wopuld pay for this, it depends really on what you want! Give them a call they are vary helpful (03) 9792-2655 2/175 Cheltenham Road, Dandenong.
Let me know how you go