Just got an email from Van Heusen. They are doing their casual shirts for £7.50 when you buy two, plus £4.95 postage per order.
I ordered six last time (about two months ago), and they were really good quality. Not such a good range this time around as only 15 to choose from, but maybe something useful for someone.
Click "clearance sale", then "£12.50 shirts" to see those available.