In most cases, I don't think the problem is the EIS but the way your options are being shown. Some of your listings show shipping to Canada with both EIS and using first class international. The listing will just show one price so to see any other prices the buyer has to click 'see details' in the shipping section or see if there are other options when they go to checkout. I don't know how eBay decides which shipping to default to but in the listings that I looked at showed first class international as the shipping cost and that was usually the most expensive price.
For example, the listing for 7 neckties shows on the search page and on the listing as $23.54 first class int'l shipping. When I click on see details I also see $18.16 for eBay international shipping. The serving platter shows an almost $10 difference between first class int'l and EIS with the latter being less expensive. The Born shoes show first class shipping as $34.86 and EIS at about $27. (these are all $US) If the Canadian is seeing your listings on .ca the prices will be higher in $C.
You also have some listings that show shipping to Canada only with first class int'l. The cocktail shaker is an example of that. That same item does have an EIS price to other countries so I'm not sure why EIS doesn't come up on Canada.
If you go to one of your listings and click on see details then change your location to Canada, you will see what Canadians see for prices. Then, view all listings to see the price that buyers will see when searching through your listings. I just quickly glanced at your listings but if first class is typically more than EIS, offering first class int'l might not be to your benefit.
Also, make sure that you are putting in dimensions and weights on all listings even if you don't need it for the domestic shipping. You have a child's book that for some reason only has EIS shipping on it at $30 to Canada. I think that the price may be high because of a lack of shipping information in the listing but I am just guessing.
