I flew AMS-MAN-AMS on CX on the same day for NLG291 (about US$134)including all taxes etc. Fare class was "W"; I booked through the American Express Travel Agency on Damrak St. downtown Amsterdam. Ph. (020) 504-8777 or fax. (020) 504-8775. You have to pay cash or charge to an AMEX.
I also flew AMS-HEL return in "N" class with Saturday stay-over for NLG686 and HEL-ARN return with Saturday stay-over for NLG467. That was a busy weekend. Finnair has a booth/office at Amsterdam airport; the Finnair rep was extremely helpful. Phone number is in the Ams. phone book.