Just found out about the company Architectronics that has developed a range of very cheap and adaptable interfaces and sensors called Make!Sense. I haven't tried them yet but intend to order a set after Easter. The neat thing about this kit is that it allows, in fact encourages students to develop their own software solutions for collecting data. This would be great for adventurous students wanting to use their programming skills. Don't worry if, like me, you can't program there is a ready made application that enables you to collect data without. I'll let you know how I get on.