The question is a good one: "Are there cupx files already built... per region?" The subject line asks about a repository for such files, which is a good idea.
It takes a good deal of effort to pull together images, annotate them to the standard of a typical club landout book, and then add them to a cupx file. It's a significant amount of work for each landout location, assuming you want more than the automated retrieval of a vertical sat image via the Google Earth API.
It does seem like it would be worthwhile to avoid having everyone who would like the most helpful CUPX file for their flying do this individually. We have consolidated CUP files for many areas so why not CUPX? Perhaps the same loose infrastructure that maintains area CUP files could take this on? Maybe it's already happening?