Here in Australia we have a comprehensive array of industry standard flavours to choose from. However, there are a few flavouring companies that are only available if importing, generally form the US or EU.
Listed below are the concentrate companies and the vendors who distribute them.
Custom Australian Concentrates
I use a lot of their flavours and find them to be excellent.
Juice Whore Signature
They produce superb tobacco concentrates and more.
Their reputation is very good but I have not tried them yet.