I don't mind sharing...... most of my damascus stock (1080, 15N20, and powdered steels) come from Kelly Cupples in Yakima, WA. I buy my stainless from
http://sb-specialty-metals.com/ (CPM steels), and for other steels I go to Aldo Bruno at
http://newjerseysteelbaron.com/. I have complete trust in all three, that I'm going to get the best quality of whatever grade I order. Personally, I think Aldo Bruno sells the best quality steel that I've found in the U.S. He maintains the best level of quality control I've seen....... when I want only the very best, Aldo is who I go to.
There was a time when you could find whatever size you might need, but those days are long gone. It's all about economics.....the producers require minimum orders so large that most resellers won't go there for fear of "sitting" on it forever. I can recall several conversations I've had with steel producers, asking them why knifemakers couldn't get the quality/quantity of the steel(s) we need....the response was: "Knifemakers are such a small percentage of our business, we really don't care what you want." At first that hit me wrong, but when you're talking about knifemakers buying steel by the pound, versus the rest of their customers buying it by the ton, its somewhat understandable.
SB specialty sells the CPM steels in up to 24" widths.(in the grades they carry)
14C28N is a Sandvik steel, so unless a reseller carries pieces in the size you mentioned, you'll likely have to straight to Sandvik to get it, and will likely be discouraged by the minimum quantity purchase required.
My advice to any knifemaker is that IF you find the steel you want, buy as much of it as you can afford...because its likely that it won't be ther tomorrow, it won't go bad on the shelf, and the prices will do nothing but increase. The last time I found "good" 1084, I purchased all the seller had at the time....and will likely never have to buy more. The other side of that coin is to be SURE of exactly what you are getting. As I mentioned previously, I've seen sellers advertise a specific grade of steel, only to discover it wasn't anywhere near what they were advertising. And when I called them on it, the response was "It's close enough!" NOT!!
The moral of the story is that its "buyer beware".