What sort of features does it have to have and what sort of design is it? If it is just a single side of copper on some acetate/plastic then that can be done easily enough if you can work a PCB design program, maybe also a knife and some glue if it is one of those ones with a thicker end on the connector side. If it is full custom connectors and such I have never found anywhere I can do it for cheap and one off or two, in fact even trying to get just one fabricated for something expensive it hard to get companies to want to do anything. I have a box of them I pull from printers and such, sometimes get lucky there (sometimes you can also find a cheap device with the same cable) and find what I want but if this is to be crammed into a small ereader that is harder still.
You might be able to fix it as there is such a thing as conductive ink. It is expensive and I don't like it much but it has got me out of a jam before. If you know somewhere that does electronics repair they will often have some and if it is only a tiny line you can try them.
Sony parts are often expensive. It can be an option to buy a more working version and scavenge the part from that -- if a battery in one has died someone might stick it on ebay for spares and repairs. A search of ebay for sony ereader gives me some cheap things and some crazy expensive things though.
