I got these great little notebooks for £1 each in a shop called Tiger, near the Discover Centre in Stratford. They're cheap versions of Moleskines, but I actually like the paper better, more like ordinary cartridge paper. It does show pen through the pages a bit, though.
Speaking of materials, Philip Reeve got an electric eraser-pen for Christmas and he's able to do all sort of things now with light trees on dark backgrounds, something that's been eluding me a bit. (I like this tree drawing in particular.) I might have to get one of those, I remember Will Kirkby (chamonkee) telling me about his electric eraser ages ago. You can see more of Philip's drawings in his Dartmoor Sketchbook and Vern, Lettuce and I make a little appearance on his year-in-pictures blog post. I think we've both had fun drawing trees, despite the chilblains and loss of fingers.