was just in alfa the other day and they should be able to supply something, though a bit over priced when compared with any of the online canadian retailers. Really your best bet is radio world in ontario...fast shipping, good prices and usually free shipping on orders over a certain amount.
Any of the commercial radio shops will have single, possibly dual band antennas availible, though at commercial prices which will be high...also they are less likely to have wide band, wide receive antennas like a ham store or radio shop.
check the source by circuit city, since they do sell scanners, and may have a mobile/bass wide band receiving antenna of some kind.
CB city at west edmonton truck land, 118ave and 170street will also have some scanner type antennas...also the flyingJ in shurwood park in the radio shop there should have something availible.
what are you looking for specifically? which freqs do you want to cover? what type of antenna mobile/bass/portible/Handheld?