Whether you need architects or architectural drafting services in Sydney really depends on several factors. If you are building a house, an architectural draftsman should do just fine but if you are in for a complex infrastructure or a skyscraper, then you will most definitely need to hire architects.
But like every other service providers, it is important to research a bit before hiring someone. Ask for at least 2-3 quotes from the company which you are looking to hire and make sure they have relevant credentials.
Some of the questions which you should ask them are:
Though the standard rate which draftsmen charge is on an hourly basis, there are many who will want a percentage of the total project cost. Before employing anyone, it is necessary to check what rate they will charge.