MindFactory.de has some cards. https://www.mindfactory.de/product_info.php/8GB-PowerColor-Radeon-RX-580-Red-Dragon-V2-Aktiv-PCIe-3-0-x16--Retail-_1173132.html

The distributors in Poland are told that the shortages are temporary and next shipment is 5-6/6/2017. Wholesalers have +1000 card orders waiting, so I don't know how long the shipment will last.

I know there more cards available in Australia, but shipping/vat is not worth it.

I've tested some RX 560 Sapphire 4GB and they run 14.5MHs 1300/2100, so half the speed of RX 470 and 60W at stock voltage. You might still be able to find some cheap RX 560 and put them into some cheap Dells/HP.

Have you considered used R9 290X or R9 280x??