Was searching for "cup dispensers" on google at work today. Don't seem to be able to find many places selling them in the UK (other than as part of vending machines/water coolers).

It did come up with this though:

http://www.plandstainless.co.uk/products/product.php?product_code=AL8500

Definitely think it would be good to get some with the lecture rooms. Now all I need to do is figure out how to mount them to the wall and fill them with plastic cups...