Refills Circled in Red
Because the Inkling at its core is just a regular pen with a bunch of electronics strapped to it, you do still need to draw real lines on your real paper. So you are going to be using real ink. Luckily the people at Wacom were smart enough to realize nobody is going to be replacing electronic pens regularly, and their ideal customers are not going to be interested in some old Bic Stic ink so they designed the Inkling to allow easy replacement of the ink reservoir.
They claim it uses a standard mini 1.0 mm ballpoint ink refill, but I have no clue what they mean by that. Nobody in the refill business will tell you that their refill will be universal because they want to make sure you buy their pen, so you are left guessing. Just what is a standard mini ink refill?
Since I don't actually have a Wacom Inkling I can't tell you exactly what refills will and won't fit it, but the Cross CRO85184 sure looks like a dead ringer. It looks a lot like the refills pictured in the product imagery and the product specs seem to match. Amid several references to ball point pens and compact and mini refill size, I don't know if I can find a better solution.
Does anybody out there know more about this setup and which pen refills specifically fit it? I can't seem to find any easily available accurate info.