I'm looking for a repository where I can get old versions of Acrobat, in particular, Acrobat 9 standard for Mac. Any help would be greatly appreciated.
Adobe does not sell older version of its applications. But there is NO Standard version for Macintosh. Hasn't been one since Acrobat 6 or thereabouts.
Your best bet is to use the associate companies with Amazon. They carry some older out-of-date stock. I just checked and a couple of them carry Acrobat 9 Professional for Mac.
I don't recommend eBay and the like because a lot of that software is pirated.