do a search covered before in fact there is a whole thread on it in General.
email harold. http://www.performancelub.com [sales@performancelub.com]
he will do you the best deal a snot retail pricing markup, check oil thread if you want more info. he is in Melb if you want pickup...$18/qt is pretty cheap.
If its std g/b I would just use MT90...not shockproof as its a GEAR OIL, not the same friction modifiers included as say mt90 or Syntrax or Syntrans...which btw are different. be fine.