Need a source of low-cost journals or other nature journaling supplies for your classroom? Here are a few resources I have found. Please add your own suggestions in the comment section.
Journals
Bear Books. These little hard-bound journals are sturdy  The standard Bear Book has 28 pages (14 sheets). The Bear Book Plus has 60 pages (30 sheets).
Sketch For Schools Journals. Spiral bound customizable journals. I recommend  the intermediate weight textured paper. You can add your school logo or other custom page to the front (though this does add cost). This might be a good place to print the naturalist tools sheet (ruler, protractor, and other tools).
Other Nature Journaling Materials
Large Drawstring Backpacks. Buy these in bulk for price discounts. Every student can customize and carry their own journal kit. The brightly colored drawstring bags run when wet so go for the white-beige bags. Sold by the dozen. Two versions: low-cost ($1.75 each), more durable ($2.25 each).
Non-photo Blue Prismacolor® Col-Erase® Pencils. Box Of 12 ($9.49)
Magnifying Glass (be sure to tie a string through the end so students can hang them around their necks.)
Crowdfunding
Having trouble raising the funds for supplies for your classroom? Try DonorsChoose.org to get money and build community support for your projects. Here are some tips: Raise Money With Crowdfunding: Top 9 Tips for Schools, Raise Money for Your School Using Crowdfunding (PDF), and Crowdfunding Tips for Students and Schools.