I have been trying to find a new notebook to take away with me to Zambia. Some ppl can make their notes and sketches on any old paper but I am a bit selective. The cover should be plain so I can choose to decorate it or not, the pages should be thin so that it is light for travel, but also means you get more pages per book (essential when I am out there where nice notebooks are hard to find) and the pages should be unlined. I succeeded on the first two but not the last requirement. Infruriatingly, all plain pages were in sketchbooks which meant they were heavy and thick. In the end I opted for Muji notebooks which are very nice, suitably nondescript but LINED! I am putting up with it and then found this amazing How To for making your own notebooks on Instructables. Will definitely try it when I have more time. It's a great website BTW, and you can download a lot of the How Tos as PDF files.
Make a 100 page Notebook - More DIY How To Projects