Perth has to my knowledge two specialist fantasy bookstores: Fantastic Planet and White Dwarf Books. I've been endeavouring to give my business to these stores in preference to the chain stores or online retailers. I'm not sure how they compare on price, but this doesn't really factor into my decision making here. Certainly any discrepancies have not been enough to notice. Even if they were to be more expensive (and I don't believe they are) having these stores available provides value that isn't available from general retailers or indeed the Internet.
Specialist stores win here because they have range and expertise. There are numerous books I've bought from specialist stores that general retailers simply don't carry because they don't have the turnover required for their business model. There are also books I've had recommended by the staff at these stores that I would not otherwise have read. Even in a general retailer carried these titles good luck finding a staff member who knows anything about it other than what's on the store's computer.
Online retailers may have the range of titles, but they're problematic on a couple of fronts. They lack immediacy as shipping can be long and expensive. It's also been my experience that they're great if you know what you want, but significantly less so if you don't. In store browsing, at least for books, beats the web experience. It also seems that in some cases I'd prefer to speak to a knowledgeable person than use a search engine, which is a somewhat surprising thing to realise about myself.
I do slip occasionally. I recently ordered The Twisted Citadel by Sara Douglass from Amazon because it doesn't seem to have a release date in Australia yet. I did try to buy it locally first though, and as a new release it's a special case. Also I'm not willing to pay twice the book cost in shipping for every title.