There are a few reasons non-photo printers are more costly at original
acquisition.
1) as mentioned they are usually designed for more durability, ease of
use, etc, because they will be moving a LOT more paper through them.
Most of the printing will be text or small graphics, meaning paper is
flying through. Also, speed is more of an issue with businesses. But
the main reason, is because the ink sales are considered in the return
the company gets.
Nonfat printers use less ink, even on photos than photo printers do,
because of the light dye load inks used (and used and used) in the photo
printers, and also, the non-photo printer may see a lot more text and
small graphic printing, again, that doesn't burn through nearly as much
ink as photo images and all the tests that often accompany them.
Lastly, the company hopes to sell specialty paper to the photo image
printer owner, while the business user often just needs cheap bond,
again no money being regenerated that way.
Art