The Gold Coast Buffet has new prices on their website. For example, breakfast and lunch are now both $7.99. Emerald card holders get $5 off, Sapphire get $3 and Ruby get $1. Not sure if this is only for January or ongoing.

New prices here: https://www.goldcoastcasino.com/dine/ports-o-call-buffet

Then scroll down on that page to see the card level discounts.