LOL how does Rockpool B&G get on that list? Seriously that place is a wanker's paradise not a cheap eat. And Spice Temple is upmarket Asian/fusion... $25 would get you one mouthful of pork belly and a contemptuous stare from the waitress.
Next you'll be telling us Tetsuyas does tightarse Tuesdays.
I think Rockpool B&G has started some sort of new lunch menu for cheap (relatively), which is supposed to be decent. Having said that, I've never been there so I can't personally vouch for it.
Wilbur's Place at Potts Point is pretty awesome for lunch - mmmm, pulled pork sandwiches.