Just bought some dry bags from here...

http://www.ewetsuits.com/acatalog/Dr...y-bags-uk.html

Excellent quality and strong materials and all at less than half the price of those found anywhere else. The 30L Overboard Grab Bag is an absolute steal at �13.00 and its ideal for the back of a bike with its yellow and reflective stripes. They're british made too! Always used Ortlieb before, not any more.