Welcome to the forum Bob, for most of my long life I've interchanged the terms "box joint" and "finger joint" however, recently fellow member and good friend George (curious George) pointed out, quite rightly, that they were not the same, the box joint is square and used not surprisingly for boxes, whilst the finger joint is longer and tapered and used for joining boards length ways.
I'm sure that it's a jig for box joints that you're after and as mentioned by another good friend of mine, Dave, otherwise known as Dr. Zook, the Oakpark spacer jigs are cheap and simple. however, they don't supply to Australia. I got mine through yet another good forum friend. You may have gathered that this is indeed a very friendly forum where it's easy to form great friendships.
Because they don't ship to Australia, I'm sure they won't mind if you fabricate your own jigs.
For starters follow this link:
http://www.routerforums.com/table-mo...-park-jig.html