Forget Upper Deck, a baseball related company actually *has* ceased operations. Cooperstown Ball Caps shuttered its doors in March, leaving behind a one stop shop for historical ball caps from major, minor, semi-pro, and other teams or designs long since forgotten. My favorite caps are from the early Musial-era Cardinals and 30's era St. Louis Browns.
The Archival Clothing blog published a details R.I.P. which includes scans from old Cooperstown catalogs here: Archival Clothing on Cooperstown Ball Caps.
Here's hoping someone picks up even a smidge of the historical designs for the baseball market. Maybe American Needle? Someone other than New Era whose caps don't appear to fit most MLB players well, much less the average fan.