Health food stores will certainly carry eucalyptus oil. The question is how much they charge and they are generally located in shopping malls/trendy areas and not so much out in the 'burbs where I live. This is very much a *niche* product and I doubt it is going to be any cheaper at the health food stores.
Shoppers typically has a very competitive price for milk and eggs and the oddballs like watch batteries (unless you want to buy on eBay from Hong Kong and wait minimum of 3 weeks for it to arrive). I do agree with you about the high markups on personal hygiene stuff though and what I normally do is look at the flyers and pick up items on sale (after comparing with major competitors of course). There are a few Shoppers within driving and walking distance from my work/office so it's actually pretty convenient for me to visit them.