Yay Shiva, a fellow Circa fan! Circa is the Levenger licensed version of the Rollabind system. The Levenger version is spiffier, with some very cool, well made discs. Now I also use Rolla products from Staples, which is Staples branded Rollabind stuff. It's not on the Staples website, but is in the local Staples at excellent prices I might add, though a sparse selection at best. I purchase full sets (covers, sheets, folder, etc.) for under $10 and cannibalize them for incorporation into my current Levenger stuff.
Getting fully on board with Circa does take a little coin because such necessitates the purchase of the hole punch. That said, Levenger does sell sample/starter kit for around $40 last I looked. That was what I got, and it came with a gift card that I turned around and spent with again. Once I tried the sample set, I think I sunk in 150-200 setting myself up with it (I run several books using the system). I have been very pleased with Circa and am now VERY excited that TB is making a Field Journal Notebook. This will only increase my Circa pleasure once I contain my daily planner in the FJN. I better watch I don't swoon when that happens. The merging of my TB and Levenger stuff into one holistic whole might erupt into a singularity of bliss that will leave me reeling for weeks!