That's what I meant by time, Roy. I guess economists probably prefer the term "opportunity cost" or something similar.
However, that assumes that producing comics must be one's full-time, primary job, and never a hobby. Especially for experimental work, I don't see why that'd need to be the case. I'm thinking more of a couple of people working with whatever materials are on-hand.
In fact, requiring an industrial scale (which is where particular kinds of paper and ink are important) probably speaks against entering the field, since it's a small audience with dollars already divvied up between the big companies.
By analogy, I'm thinking more YouTube than Hulu, if you get my meaning. You can spend a good amount of money on a large-scale production like Battleground getting everything picture-perfect in hopes of getting distribution. Or you can work on a shoestring like Aiden 5 or The Lizzie Bennet Diaries (in early seasons, also The Guild, before Felicia Day was able to make is sustainable through sponsorship) because it's fun, and let the audience find you.
I won't suggest either model is better, since I actually liked Battleground, but the cheaper approach seems to work pretty well. For example, with only an episode or two more to go, this week The Lizzie Bennet Diaries is about to hit a quarter-million dollars raised on Kickstarter though almost four thousand pledges after two days, with another four weeks to go.