I don’t see why not. In some ways, that may be even better than simply buying a cheap notebook. If you have a decent amount of blank line paper, putting them together and sticking the spine together to create a makeshift book should suffice. You should also consider looking around your home for any unused or partially used notebooks. I made mine by finding a cheap dollar store notebook that I never used, and i stapled on blank sheets of paper to the front and back…then colored it the correct colors, and glued on the sigils. Very cheap, very makeshift.
Another thing you should consider, if money is really tight, is looking through this thread and scroll through the section titled Money Magick. There, you will find success stories of many different users…and within them, you may find a spirit or a technique that resonates with you and your situation.