In reply to Morgan Woods:
They start at £3.50 (which seems about average for all the brands) for the shortest. I know just buying one or two isn't too much but I need at least ten so it adds up and I'm temporarily a student once more so a bit skint!
I was wondering if anyone had seen a shop that does packs, perhaps from one of the Eastern European brands like Singing Rock, for less. Oddly I've seen at least on one French webshop, they sell DMM ones for less in Euros than you pay in pounds in the UK! I think its €10 shipping but even including that, if I buy enough its marginally less than from one of the good British webshops. Interesting how the economics of that works out.