The importer is an added mouth in the food chain. For Domestic kits there is the manufacturer, distributor and retailer. For imported kits there is Manufacturer, importer, distributor and retailer. There may be some import duty involved but I don't know for sure about that.
Once I saw on the shelf at the LHS a Lindberg Bugatti Royale, a Gunze Sangyo release of the same kit, and then the Revell Germany Import version of the Gunze release! Each one was marked higher! I think the Lindberg was in the $10.00 range and the Revell Germany import was $25.00