I suspect you won't find a single mass market for this. The mass market is well served by generically designed notebooks.
Instead, you'll find a number of highly profitable niche markets. (Like the D&D crowd, the design crowd, the hacker crowd, STEM teachers, etc.) Judging by your homepage, it seems you're already on this track.
Because of this, your best bet (once developed or at least in early testing) might be to find a few brand ambassadors from each of those niches: a dedicated gamer, a well-known designer, etc. People who can introduce your product into their respective niches.
I'd also make sure the print quality is on par with Field Notes or Moleskin, to make sure you can command a good price.
Apologies for the unsolicited advice... just really into this idea.