I don’t have my original birth certificate; what can I do?
1) Apply for a new birth certificate. As of 28 July 2014, this price for this service was €20 + €2 postage to Australia though this is subject to change. You should allow two weeks for your new certificate to arrive.
2) If you need to get hold of a certificate sooner and know the location of your original birth certificate in Ireland, you can ask someone who has access to it to make a certified copy of it at a local Garda Station and have that copy scanned and emailed to the Embassy.