I shoot 8X10, black and white in studio. A normal sitting takes me about two hours of time including prep for a total of 6 to 10 exposures. Most of my final prints are between 11X14 and 16X20 in size.
If these are darkroom prints, I'd have to charge thousands. That is a lot of work even with an assistant.

If providing inkjet prints I'd ditch the 8x10, use a DSLR and make money on the deal.