My 2c.
Head unit is a good start and will have plenty of support if purchased locally.
Speakers I would demo, may be marginally better that the factory units or they could be gr8, but you can't tell on-line.
Demo some gear and decide what you like, you don't have to get everything at once. Build your system slowly if your budget won't stretch.
I suggest if your close to them, get yourself down to Call Frankston Car Audio and have a chat with Mark the prop. He is offering insane deals on quality gear right now.
http://www.frankstoncaraudio.com.au/attachments/File/OzblissClearancePoster.jpg
Crescendo Opus