Given the price, I'm taking it that you REALLY want this, and that money isn't really an object.

You need to sign up for a US based remailing service, then list that as your "main address" in ebay, then buy it now and pay the fifty bucks shipping. You'll then only have to pay courier prices to have it shipped over here.

I use shipito.com, very reliable and you can have it set up in just a few minutes work. They give you a special address (you can choose where in the USA, but usually there's not too much of an advantage) and vioila. One tomy train set for you in less than a fortnight's time.

eg
David Reilly
c/o Eastbiz Corp. ?
2972 Columbia St.
Suite # 17550
Torrance, CA 90503
USA

If you have trouble adding a US address to your AU ebay account, they will also do "personal shopping". Its very much more expensive, but again its still an option for you.

They also do Japan addresses for you too, if you're a Takara fan.