Found this offer on the Tripadvisor's Get Offers page, spend $150 and get $50 back on American Express Travel.
Save this offer to your Card to receive a $50 statement credit, when you spend $150 on pre-paid hotels, car hire or experiences at americanexpress.com.au/travel by 31 January 2015. Offer limited to first 15,000 Cards.
This offer is valid for purchases made within Australia, in AUD and charged to an eligible, connected Australian American Express Card.
Hmmm is this AMEX only issued cards or also AMEX bank issued? I can only see this in the T&C's:
B. Eligibility
Eligible Cards
Only consumer Cards issued in Australia by American Express Australia Limited or a licensed third party issuer are eligible for registration (eligible Card). The following Cards are not eligible: prepaid Cards, gift Cards and corporate Cards.