Stainless steel is a great material but there is a reason that common kitchen appliances and counters/backsplashes are not made from it and that is that it is much harder to fabricate. You have to use a shear to cut it in large pieces and a break to bend it. While you can get by with a pretty cheap shear and break for light gauge carbon and galvanized steel, the ones that you need for dealing with stainless are much more expensive. Since they are heavier machines, they are not as mobile either.
You will have to call a pro to measure and fabricate the sheet stainless for your backsplash so why not just have a pro do the whole job? I know of several shops in the Detroit area that can do the fab work and, if I wanted a stainless backsplash, I would start by talking to them. Restaurant supply houses also have sources.
Stainless steel is not particularly fabrication friendly and it is expensive.