I looked at your Instagram page here, lots of very,very nice cuts!
Hairdresser (@andrewdoeshair) • Instagram photos and videos
I'd rather have a digital file to print from instead of printing from a negative.In this, 2017, the vast majority of print places today are printing not from negatives, but from digital files. As far as prints go, there are multiple surface types. Smooth, glossy-finished papers will show more fine detail and will look very sharp and crisp at close viewing distances, but can also show glares/reflections from lights when mounted on walls. Matte paper does not show glares from lights hardly at all, but it greatly reduces the sense of sharpness and fine detail on high-frequency details, like hair, or leaves,etc..
"Metal prints" might be worth looking into. I have no knowledge of your place in the industry, nor the culture of it, so I have no idea about selling haircut/hair style prints to people in that industry. Not sure if film is the right capture medium, but there is a film type for almost every look. Slow-speed color slide film, slow-speed color negative, medium-speed filsms, high-speed films, low-contrast pro color negative films...all have a slightly different look from one another.
Pardon my lack of understanding, but I do not truly know what the market for these types of photos is. I am not familiar with what peoople might want in these types of photos. But I do think it might be a good idea to make these shots in series form; maybe using say one type of barber's cape for 12-20 images, or one type of backdrop, something to unify them, so there's a bit more of a temptation to make them "wall art for the shop". Not really sure what the market is though: I do not fully understand who the target audience really is.