There were less than 9000 Auto Mags made and they had two different diameter recoils springs and Wolff usually has them in stock. I would be surprised if there are more than a couple thousand Auto Mags still being shot today after 35 years.
Also, this AutoMag situation is totally different. Wolff has been the sole supplier of AutoMag springs for a gun from a defunct company. There is a (small) market of people who NEED your springs. You can sell them, and probably at a premium if you want.
For the past decade or so, Wolff would have been only a secondary supplier of its own Rohrbaugh springs... Most private buyers would probably buy from Rohrbaugh. Wolff has much less incentive to sell to the public on a piece-by-piece when you can just sell your whole run in bulk to Rohrbaugh.
Now, however, there is a market again. At least for the moment they are the sole supplier of springs. And once Remington cranks up production, they will likely source their own springs. If they do, Wolff still has a market to compete with "no name" springs from Remington.
As an aside, I bet Wolff hasn't run AutoMag springs in years. They do one run of 500 springs and they can stock them for many years.