It's difficult to shop for touring-capable 700c wheels, because >95% of them are intended for racy road bikes - low spoke count, narrow rims - both unsuited for durability under perhaps 250-300 lbs load. Even the once standard 32h road racing wheels are now rare.
As others have already stated, you'll want to choose 36h for added wheel longevity, these can still be found. If you go to 40h or 48h it really narrows your choices of available rims and hubs, and also becomes more expensive. Dynohub also narrows choices and raises price.
Many tourists resort to custom wheel builds to get what they want, again more expensive than wheels mass produced to a price point. Some of us even build our own wheels, since it's not that hard and basic tools are cheap ($5 spoke wrench). DIY can be inexpensive and get you the wheel you want.
Shimano Deore, LX, XT hubs are very popular because they're a consistent good value. Hope and DT makes good mid-level hubs, and Phil Wood at the top of the cost range.
DT Swiss and Wheelsmith spokes are very popular, either straight gauge 2.0mm or butted gauge 1.7-1.8/2.0mm. Some choose DT Alpine for heavy duty uses, very strong but very expensive. Plain ole straight gauge spokes work fine and usually cost about half as much as butted, which will add $30 or more to the cost of a wheelset.
Rims are the hardest choice because there are so many available. Because touring usually involves wider, heavier tires, it makes sense to use a wider rim, which is naturally heavier. Rim width is usually indicated as inside width, add ~5mm to determine outside width. There are a lot of disc-only rims nowadays, they are nearly the same as rim-brake-compatible rims, they simply lack a flat brake track, the sides are angled towards the spoke holes, which looks nice and saves material/weight. Rims with a brake track can be used for both rim and disc braked wheels.
Leading rim makers are Mavic and Velocity, these are used widely by custom and self builders. DT Swiss are popular but expensive. Alex are also popular for mass produced wheels, because they are very inexpensive. Despite their cheapness they seem to hold up well. Surly has used the Alex Adventurer rim since 2004 for the complete LHT with very few complaints. Alex rims cost 25-45 USD, vs 50-80 for Velocity, 50-100 for Mavic, 70-120 for DT Swiss - so you can see why Alex rims are so popular in built wheels. I used Alex TD17 rims ($22) for my wheel build for a Surly DT, they are fine after ~1000 miles so far. Hard to not like Alex when I've gotten the same results with $70 rims.
Nipples are made in brass and aluminum. Al cost more and saves weight, but they break a lot more often than brass. Brass is the way to go to keep it simple.
Front and rear wheels, hubs or rims don't have to match, although most people buy them this way. For touring (and even non-touring) most (60-75%) of the load is on the rear wheel. If you have to cut costs, cut on the front wheel, put your money in the rear wheel. A custom 48h rear and a plain 36h front will work.
I hesitate to make specific recommendations since things that are a good deal here in USA are not necessarily so in Australia. I googled "touring wheels", here's a few interesting finds:
http://store.velocityusa.com/p/dyad-...uring-wheelset
http://www.co-motion.com/index.php/p...uring-wheelset
http://www.rivbike.com/product-p/18103.htm +
http://www.rivbike.com/product-p/18102.htm
http://www.aebike.com/Handspun-Pavem...r_p_31663.html +
http://www.aebike.com/Handspun-Pavem...r_p_31557.html