I've spent a bit of time at Sydney Airport over the past year or so flying domestically, and I thought it was about time I plugged the following place:

Joe & The Juice - T2 Domestic Terminal (for Virgin, Jetstar, Tiger), located straight ahead from the stairs/escalators you head down once going through security screening.

Not only are their coffees reasonably priced, they have consistently served me excellent coffee every time I have been at the airport. There are four separate colour-coded takeaway cup sizes ranging from the small demitasse up to the big sugar buckets - interestingly they don't appear to have an 8oz size cup however I actually prefer my usual fare (strong flat white) to be more like a large piccolo, so the second-smallest cup (perhaps 5 or 6 oz) appeals to me.

This appears to be a bit of an international franchise chain - I've not noticed them anywhere other than at the T2 Domestic Terminal. At an airport where inflated prices are the norm, not to mention the likely sleep-deprivation associated with travel, their coffee is extremely welcome and in my opinion as good as anywhere. They also do fresh juices however I have not tried any of these.