nads,
I currently have a block that has more then doubled in 13 months of ownership. It's an infill block, vacant with homes on either side, with this approach you get a feel for the street, nice surrounding homes can assist in your appreciation. With a new estate your going in sight unseen and there is the matter of scarcity, is it stage 1 of a multi stage release.
In all cases it is demand pushing up the price, that's why I like selective coastal areas, Bernard Salt in The Big Shift refers to the 'push from the bush' and the 'clamour for the coast'. I believe Australians will be clamouring for coastal property for some time to come. Apollo Bay is a great example of a 'Sea Change' town that has become very trendy to weekend in and retire to, why should this change in the next 10 years. If AB is out of your reach look for the next town in the ripple effect. Where are all the people going that can't afford AB.
Obstacles include the extra time it takes in finding the right property, we tend to include weekends camping up and down the coast with looking at real estate. Finance is also more difficult the more speculative your purchase.