How about Ray Price, Ken and Dick Thornett? IIRC all were current Wallabies when they moved across to League. In earlier times, Arthur Summons (I think was the current Wallaby captain) and Keith Holman. There are plenty of others.
Ken Thornett never played for the Wallabies. I am almost certain Keith Holman never played rugby at all. But you are right, there were plenty of others. Pretty much every season we would lose 2 or 3 rep players.