I can't help you with Australia retailers/shipping, but I can give you my thoughts after, like you, going down this road about four or five years ago.
For soldiers, I like 1/72 plastic kits. They get a bad rap because they are soft plastic, and indeed, that means you have to spend more time prepping them. My favorite manufacturers are Pegasus Hobbies, Caesar and Revell. Each of these companies sculpts well detailed properly proportioned figures in natural looking poses (less so Revell).
To get the most out of them, however, you do have to prep them. You should scrub the sprues with dish soap (I use my hands, not a sponge or brush, mileage may vary). Once they're dry you should assemble them, testing assembly with either specialized plastic glue (like testors liquid cement for plastic models
http://www.testors.com/product/136635/3507AT/_/Liquid_Cement_1_Oz.) or normal super glue. The plastic kits have different types of plastics that respond differently to different types of glue. Usually the testors liquid cement works best, but not always. For example, I found that the Pegasus Hobbies SS at Kursk sets go together much better (and quite easily) with normal super glue. Most kits don't actually require assembly...most just require cutting off the sprues or cutting the flash. But particularly detailed kits, like the pegasus one, and the Plastic Soldier Company ones, due require assembly.
Once you've assembled the figures (if required), glue them to a base. I use 5/8" diameter round washers with a 1/4" diameter hole in the middle. This allows me to magnetically mount the individual figures on larger 1 1/4" bases for games that require multiple figure bases (like Crossfire). The 1/4" diameter hole is usually covered by the plastic figure's integral base, and then I glue a rare earth magnet in that 1/4" hole underneath the figure to make the whole thing magnetic. I know in the UK modellers prefer to use one pence coins. Base however you prefer, but I strongly suggest a base with a little bit of heft to it since the figures themselves are light and plastic.
Once on the bases, water down some white/PVA glue and "paint" it on the figures. The white glue should be watered down enough to dry completely clear. This is my most important step, and I can't even point to the exact reason why I do it. My first two boxes of figures I pained by just priming the figures with spray primer. They turned out okay. The paint didn't flake or chip or anything. But they always felt like soft bendy plastic. I then experimented with the white glue treatment and I haven't looked back since. This step really stiffens the plastic and makes it feel like hard plastic. It also makes the figure less prone to breaking, and the guns less likely to bend.
Then, you start painting it like a normal metal figure. First you prime it and then paint away. I've found that the white glue treatment acts like primer on some figures but not on others. So for the sake of being sure, I just prime over the white glue.
The white glue treatment does kill some detail on the figures, but to my mind it's worth it.
The figure companies I like that I mentioned produce figures with a different style than most 28mm figures. They have more natural proportions. The metal figures that seem to have that same style are AB figures, though I've only seen them on the web, I haven't seen them in person.
Metal figures I have seen in person are Platoon 20 and FAA. I wouldn't recommend the former; I did like the latter. They are both sculpted in the 28mm exaggerated style. If you like that style, Plastic Soldier Company also makes excellent hard plastic figures in that style. Other metal figures I can't comment on, but the Guild Wargamers page will give you a lot of great information.
Finally, check out Plastic Soldier Review before buying your figures. They'll give you a wealth of information on uniforms and weapons, as well the average size of the figures (so you know if they'll look out of scale with your others) and pictures of every pose (so you know if they'll work with your favorite rules set).
As for vehicles, perhaps it's different in Australia, but I've found the pre-painted ones to be quite pricey. When I first started down this road you could get Forces of Valor toys for ten dollars each, but no longer.
The introduction level plastic kits are quite a bargain. Armourfast, Pegasus Hobbies, Plastic Soldier Company and Italeri Fast Assembly models are all "easy builds" kits that come with multiple vehicles per box, at about 7 or 8 dollars per vehicle. I recommend using a specialized plastic cement like the testors, above, to put these together.
I've found Esci and Airfix models to be more complicated than the easy build kits above, but still a fun project for a beginner modeler like myself. Models can get significantly more complicated, intimidating and frustrating depending on manufacturer, though, so beware.
Lastly, start visiting model shops in addition to your FLGS. In my area, at least, the FLGS carry nothing but 15mm models (for flames of war) and GW models. I don't think it's their fault, per se, I just think they've been squeezed so hard by the economy and the constriction of the hobby gaming industry that they can't afford to offer the wide range of product they could in the seventies and eighties.