Certificate Authorities (The companies who issue the Certificates eg Comodo, Symantec, Geotrust ) are overseas based. We therefor have to purchase from them in USD. Because exchange rates change all the time and we sell our products onto you in AUD at highly reduced prices we need to constantly update our prices in relation to how much we buy them for. You will notice the prices go up and down each day by a few cents. We also do larger price reductions when we can buy them at a lower rate due to more bulk buying.