I saw a promotion on the MTR for 40% off your Airport Express ticket when using Visa Platinum, Signature, or Infinite. I think this is an awesome deal making your trip only $60 from Hong Kong Station.
Details can be found below or through this link.
The main caveat appears that you need to order it online, and the web site says you need to use a credit card issued in Hong Kong, but I can’t see how MTR would really be able to check this.
This promotion is valid for tickets through December 31.