MR2Heaven.com is where I got my ST185 cables. They are reproduction cables, but are good quality after a year or so of use now.
Also, there is a thread in the drive-train section on shifter cables. I have a post on the lengths the cables in there. There are a pair of cables and both must be cut, shortened and the ends welded back on. It was actually not that hard with my cheap 110v welder. They bolt right in after trimming.