Amazon.com.au just dropped the price on 500ml bottles of Herbin Perle Noire ink, sold and shipped by Amazon UK, to $45.92. Includes free delivery to Australia to Prime members here.
OK, that isn't cheaper than I could have scored from La Couronne du Comte before it went out of business, with stacked discounts, no GST paid, and (as part of a large enough order) free international shipping; but it comes pretty close. With LCdC now gone, I don't think I can do much better in the near term ordering from any other retailer.