I don't know... only FOUR decks to last for 910 shows over four seasons? I'd wager that it's more like there were four at any given time and that periodically replacements were made - not a lot of them, to be certain, but I can't see just four decks lasting through all that wear and tear on the set of a game show. You know yourself from handling them how difficult they are to shuffle, and you couldn't leave them unshuffled from show to show - some damage between shows must have occurred, requiring new decks to be printed. I think my number of a dozen is a good one, but it's just an educated guess, and just as the shows themselves weren't saved (much to the chagrin of the Game Show Network, I'm sure), the records indicating how many were made any by whom may also be long gone.
If you DID know the name of the manufacturer, there's a fair shot they'd have the records. Some businesses keep their records a VERY long time - the cards were probably made by a print shop somewhere in LA, and probably not far from the studio. It would be a matter of whether that business was still in business, of course, but if they are, you might be one step closer to more info about those cards.
On the one hand, I'm not surprised that the shows were considered somewhat "disposable," but on the other hand, any program that makes it to 65 episodes has a good chance of getting sold into syndication - 65 episodes allows for 13 weeks of air time without a repeated episode, five days a week. I'm shocked that this wasn't considered, but then again, game shows didn't get syndicated in reruns anywhere near as often as dramas and comedies. Even to this day, there's not much call for reruns of game shows outside of GSN, but then again, there's not many game shows left (unless you count primetime "reality" game shows like Survivor). I know "Let's Make a Deal" and "The Dating Game" were on in reruns for a while, but they were kind of whacky and offbeat, not as straightforward. LMAD had the crazy audience costumes and TDG was kind of like proto-reality TV!