This seems to be a pretty good price for the genuine Sony memory stick duo pro - only £15.42 including free super saver delivery for amazon. It would be a hnady enough purchase if you only fancied a 512mb card, and didn't want to spend as much on a 1gb card.
Details: The MSX-M512S Memory Stick PRO Duo media provides unbeatable storage value for your compact digital camera, camcorder or portable audio device. With 512 megabytes storage capacity with 220 megabytes available, it provides plenty of storage space at an unbeatable price. The MSX-M512S has an expanded operating temperature range making it ideal for use in a variety of different environments.