For those that might need this runner in the future, I suggest you contact Aquaware America. They are the importer of this Cesana shower enclosure. Memory is not what it once was but I think that the cost of the runner, including shipping, was south of $40 by a good bit. Quick service and nice folks.
You can find their 800 number at the bottom of their web page. www.aquawareamerica.com/
You can get the part numbers you need at this web page. http://www.cesana.it/cataloghi_file/Serie%20Circle_Radius_spare%20parts2.pdf
Note that you could make a quick run to Italy and get the runner for under $14! (Don't tell your wife!)
(If someone could explain to me how to make a link out of this I would really appreciate it. I have tried every way to express it that I can think of but the preview always includes the code.)
Bruce