Another point to consider is who made the "aftermarket" part. Example I have experienced; Behr makes radiators for MB. If you buy a Behr radiator from an aftermarket supplier it will cost much less than a radiator from the dealer. The difference? The "MB" logo is missing from the Behr "aftermarket" radiator. I noticed this with BMW also.
92 Volvo 740 Wagon aka "Mutt mover"