Amazon UK lists no Obihai items at all except a used 1032 phone from a third party.
Amazon Germany lists only OBi100 and Obi110.
Amazon France lists OBi302, OBi100, ObiWIFI (not the 5 GHz capable one), OBiBT, OBi200, OBi300, OBi110, OBi508vs and OBiLINE.
It looks like only Amazon US is currently getting stock. Whether the reason is Obihai or Amazon I won't guess. Amazon elsewhere seem to just have what hasn't been sold since their last supply.
The only difference between the US, UK, EU and AU models has been the PSU inside the carton and which box is ticked on the label on the outside. There is nothing special about the PSU - any decent 12 volt 1 amp unit with the right size plug and centre positive will be fine. Lavarock obtains a US model and sends it to Oz where a PSU is obtained locally. Or assuming the US PSU is a 100-240 volt type, get a US pins to AU pins adaptor.