Hi Christianlebe, and firstly welcome to SaleHoo
In regards to if it makes sense, the theory behind the idea is very sound. It shows you're thinking about the structure of your business and how it impacts on your customers, and that's one of the most important aspects of any starting any business.
Of course whether or not you can implement that comes down to finding the right suppliers. My advice would be to split that into two plans, so number one would be to source locally, number two would be to open it up to international suppliers if number one wasn't a practical option for you
You could of course also consider number three, a combination of both. That could give you a core product range with fast turn around, then give you a wider range of products as a secondary range where shipping is slower, but well worth it for the customer because of what the products are.
In regards to does DS work in Australia, it's not country specific. It's about having the right processes in place to provide as good of a service to your customers as possible. With DS, there are always going to be things outside of your direct control, but you have to minimise those as much as possible.
Key problems areas for DS, no matter what country, are things such as supplier reliability, supplier communication and suppliers assistance in the event of a problem. Item lost in the mail, broken or substandard to what the customer was expecting.
When you have issues like these, you need a supplier that will respond quickly to the issue and have procedures in place to assist with a fast satisfactory remedy for both you and the customer.
Good Drop Shippers understand that you are an asset to their business and they will service you as such. Bad Drop Shippers tend to just chew customers up and spit them out as they feel that there will always be new customers coming through for them.