If your only going to be spending $40AUD a rim then it would be too expensive to get a wheelset. I'm not sure about spokes, some say you should replace them others say you can't. Dont worry about the hub, just give it a service (clean out grease/re-grease) and that will make a big differnce. The hubs look like basic stock OEM shimano ones or something, nothing spectacular and unless you're having problems with them dont bother replacing them.
A rim will be cheaper then buying a wheelset. Yes a wheelset is 'more for your money' if your looking at building up a whole wheel. If you feel you dont need knew hubs then dont bother with a new wheelset, just buy the rims you want and get them fitted.
Call up a few LBS's tommorow (to get a rough idea of general costs) and ask how much it would cost for them to build re-build your wheel/s with a new rim/s.