Members of the Operational Research Society and proven Members of affiliated EURO national OR Societies (http://www.euro-online.org/display.php?page=societies&) can claim discounted fees of around 20%. 

Students recieve a discount of c. 70% 

Also see the very restricted Assisted Places Scheme with deadline of 30th June

http://www.orsoc.org.uk/orshop/(nusgkj55o3zmft45bu5di5fy)/orcontent.aspx?inc=or50_assisted.htm