Having lived in Melbourne a Mac would be good for both work and casual wear. A Pea Coat by all means and definitely a rain coat as opposed to a jacket guess it depends how far you have to walk to tram or train.
J Crew had a good selection of jackets on sale and i picked a pea coat up for $120 oz I think plus the $10 shipping.
I don't know what a good Mac would cost brand new close to a grand? and for that sort of money you could invest in a good Trench which would be both rain, work and casual proficient.
As I have said before, I think a Mac with a removeable liner covers all your bases in Melbourne, work outer-wear wise.
Quite a few places sell them, you can pay anywhere from $300 - $1k. I have one from MJ Bale which was a steal at $200, and a thinner one from Jack Spade which cost twice as much as isn't as good quality!
My outerwear wardrobe is fairly well in line with tobias described:
Casual I have
- Rain Slicker
- Short Duffle
- Canvas 4 pocket biker jacket - good for weekends down at my gf's farm or anywhere I don't want to be too dressy
- Multiple woolen jumpers & hoodies
+ soon to add a quilted jacket from Luxire with a detachable hood
Navy mac, beige mac.
(Trenchcoats and macs are, IMO, essentially interchangeable - whichever style you prefer. They do the same job and provide a similar amount of warmth. Trenchcoats are just a bit too fiddly for me, I prefer the plain/sleek look of a mac with slit pockets).
Probably the only gap there is a topcoat of some kind for work - but I just never get that cold in Melbourne, and I hate feeling "chunky" on PT etc. I run hot in general, so a Mac + a suit + gloves + maybe a v neck is all I ever need. It just isn't that cold here.