Do the math on the cost/sf on the Canon and Epson printers. Ink consumption is pretty steady, usually no more than 1-2ccs per square foot at the most. With the 700ml carts on the Epson 9900, that amounts to .36-.72 per square foot. Add your favorite paper or canvas, say some nice Epson Exhibition Fiber paper at perhaps $1.80/sf, your total cost per would run about $2.52 max. Add say 25% for wastage on material, ink, cleaning, you are about $3.15 per sf and I think I'm on the high side when I consider my materials, etc.
Compared to sending out the work or running in a dark room, these costs are pretty low, IMO. I know when I used to run C-prints and Ciba/Ilfochorme, it was much, much higher, especially the time and labor it took to do these processes. Factor in inflation, from 15-20 years ago…
I'd say rather than worry about the material costs here, find a fair price for the quality of the work you are doing and then just do it. If you are looking for lowest price to compete with a bulk lab or wallyworld, don't. It's not worth the aggravation. Spend a little more, be a little bit better and just do it.