This afternoon I dropped by Sherwin-Williams to pick up some paint for the desperately-needing-to-be-painted living room and noticed some rolls of craft paper, cheap, that looked promising for journal making. I picked up a few and immediately drove home to try them out. Maisey and I had fun experimenting with spray paint and our new paper rolls until the mosquitoes forced us in. The smaller rolls varied in width from about 4 in. to about 10 in. The paper itself is pretty thin but still strong enough to stand up against latex paint. Much stronger than newsprint but about the same thickness. These were labeled as "General Purpose Masking Paper" and, best of all, they were only about $3-5 a roll.
The store also had large rolls of "Builder's Paper"--which you may be able to find at your local hardware store, too. It's quite a lot thicker than the masking paper and about a yard or so wide. It absorbed a bit of the spray paint leaving a more delicate coloring, but also worked great with Maisey's finger paints and acrylics. And it was a steal at $9 a roll.
I love finding a new inexpensive paper source! So, go check it out. Then come back and share your own experiments--I'd love to hear about them!