That is true - but some land is just as expensive as a pre-existing house. For example, it is rare to be able to find a decent block of land up here on the coast for under $300,000 - whereas we could sell this house for around the same. And I can tell you that the stamp duty paid to buy this house would be a HEAP lower (especially as new thresholds have been introduced) than it would be to by a block of land.

Its on the value of the land for sure - but only works out cheaper IF you manage to get a reasonably cheap block of land.
You are right of course, But I really think that the ACT is a market unlike any other in Australia. There is no such thing as a cheap block of land here, the cheapest is about $200,000 for 300-400m2 - stamp duty on this is about $5,500. It costs at least another $200,000 to build a basic 3bd home on that. House prices for a pre-existing 3bd home in ACT start at about the $400,000 mark ($17,000 in stamp duty). If you can manage to find an older house on a bigger block (say 500 - 600m2) for about the same price, you tend to be missing things like a garage. I only know this because this is what we have been looking at for the past 3 months.

Of course if you are actually lucky enough to find a property for under $320,000 and meet all the requirements for the stamp duty concession (ie, first home owner, owner occupier), then stamp duty is greatly discounted ($20 per thousand dollars of purchase price).

I guess it depends on if you are buying as a first home owner or not as much as anything else. From an investment perspective I would certainly consider older properties that have more land in comparision to new houses. But DH and I have already decided that when we are ready to upgrade our Primary residence, then we will certainly be building new - so we can get what we want.

NSW is a completely different story all together, and really depends on where you live. Regional NSW varies greatly from inner sydney