One other way to save a bit of dosh on your nosh- is to eat at a pub. You will have to scout your pubs carefully, some are tragically expensive. Then there are the few local beauties that offer $5 steak day, Free steak with the purchase of a beverage (oh darn), Trivia night with half price mains, etc.
If you are wiley and have the time between parties to scout it out- I reckon (Aussie for: I would imagine you would find it so..) you could find a local pub or Thai restaurant with a special every night of the week. Hotel Mosman and The Slip Inn are two notorious locations for $6 meals every night with the purchase of a drink (again- oh darn). Many pubs and eating establishments in the CBD of Sydney have a set menu and drink specials during the week as well. Jacksons on George is well known for it’s drink specials.
Make sure you read the banners on the outside of the pubs to find out when the good deals are.