Print your own manuscript paper!
I have been working on my manuscript paper collection. It seems successful and there are three pages, some with a choice of density. The .pdf versions are the easiest to use, but are fixed. If you download and save the Word versions you can then tinker with them to suit your own requirements. The .pdf versions may be printed straight from the Acrobat reader. (Click the printer icon in the Acrobat tool bar.) Don't be put off by the appearance of the pages on your monitor, they do print properly!
Here are the .pdf versions:-
* There is a CDROM available from Boosey and Hawkes which has a huge range of this sort of thing. I have an (unopened!) copy in stock (£15.00 or so). The pages offered here are all my own work and are not copied. You may copy them. Do feel free to use them as the basis of your own experimentation.