A hacker-publisher friend does "print-on-demand" the simple way; a high-end laser printer plus a high-end perfect binder and cutter. I think they kept their equipment costs down below $10K. The standalone machines don't do much besides print and bind and I believe cost much more.
This is a solution for a low print run rather one-of-kind printing but it works for him.
In the realm of thesis printing, you pay 10 to 22 cents per monochrome side, plus about $30 for perfect binding (plus shipping, and any surcharges for fast turnaround). So printing Strousup's 900 page "The C++ Programming Language" costs $130+ and printing something slimmer like "The Art of Computer Programming, Volume 4 Fascile 4" costs $40+. New from Amazon those would cost $55 and $15 respectively.
If you can get your prices competitive, there might be an opportunity for you in thesis printing.
If you could get your prices so low that a professor with a ready-to-go textbook in PDF form could get it printed on demand cheaper than going through regular publishers and college bookstores, that would be a big opportunity right there. By all accounts college textbooks in America are very expensive, but neither authors nor publishers admit to making much profit, so presumably there's a lot of inefficiency there. Could be ripe for disruption.