I think mine came from Canadian Tire, but I've seen them at Walmart etc.
They will attach to a dash vent too, but I drilled 2 holes in the door. The
brand is "Type S" by Winplus ??
Google it  :)
Looks like it might be discontinued...closest match I could see
http://www.myfortune3cart.com/Winplusna/Drink_Holders-DRINK_HOLDER_VENT_SCULPTED_GREY.html
http://inpcars.com/dash-mounted-holders/3.html
http://www.cartuningparts.co.uk/type-s-universal-carvan-air-vent-drinkcup-holder-silver/
http://www.amazon.co.uk/Type-DH10081-Adjustable-Drink-Holder/dp/B0009N4F7C
http://www.kaboodle.com/reviews/type-s-dh-10081-6-vent-drink-holder-silver
http://www.ragingspeed.com/UK/product_info.php?products_id=217
http://discount-cabin.com/shop/product_info.php/type-10081-vent-drink-holder-silver-p-312475

Tom