Since I have a preference for heavier paper, which allows me to use gouache, watercolor, or acrylic without buckling. I would gather up paper in the weight, texture, size and tint I desire, and take it to a printer (or office supply) that offers binding and voila! I haven't done this in a while, but an artist friend still puts his together that way and it runs him $5 to $10 depending on the dimensions.
Daler-Rowney has a good ecru-warm brown hardbound sketchbook as well has some respectable pastel pads in a variety of hues. The latter are not high end for pastel work, but are quite satsifactory for sketching and are heavy enough for moderate gouache applications without issue. Aquabee has a Bogus (recycled paper) sketch pad in 9x12 that is a greyish brown ( I have used the loose sheets and it has good texture for pencil and charcoal). And Canson has some wonderful sketchbooks that are a cream or manilla tone.
"Channeling is just bad ventriloquism. You use another voice, but people can see your lips moving." -- Penn Jillette