I've been buying stuff off EYO for a few years now http://www.eyo.com.au/. I love their website and if you email their sales people you get good recommendations even if you ask something technical (i.e. about VT Processors)

Another online supplier is http://www.altech.com.au I haven't used them but they also are in the same genre although the website wasn't as easy to use (however I think they have just updated it so it may have changed).

For PC/Printer memory I have used these guys www.computermemoryupgrades.com.au and when HP quotes a thousand dollars for a stick of printer RAM they come in at less than a tenth of the price.