There are 2 on the US eBay:

http://cgi.ebay.com/Williams-Pinball-Machine-EM-Chime-unit_W0QQitemZ150357000608QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item2301f9c1a0&_trksid=p3286.c0.m14&_trkparms=65%3A1%7C66%3A2%7C39%3A1%7C293%3A1%7C294%3A50

http://cgi.ebay.com/Williams-Sonic-Butterfly-Pinball-Machine-EM-Chime-unit_W0QQitemZ160347686238QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item255577855e&_trksid=p3286.c0.m14&_trkparms=65%3A1%7C66%3A2%7C39%3A1%7C293%3A1%7C294%3A50

Even if they don't state they will ship to Australia, I find most of them will if you email them and ask.

If this doesn't work try RGP or a wanted to buy ad on www.mrpinball.com