In the 'States, EuropeanAutomotiveSpeacilists has 1993 400E rebuilt front left/right calipers for $123.96(includes the $35 core charge) per side. The 1993 400E front brake discs range from roughly $57/disc for regular discs to $111/disc for Zimmermann cross-drilled ones.
So thats: $248+$114= $362
Shipping would be the determining factor, since shipping to the Lower 48 'States is free if total is over $50.
Maybe one of your fellow countrymen know of better cheaper place in Canada.
That $500CDN isn't a bad price at all if it includes all new parts. Might want to think of stainless brakes lines aswell.