My normal carry gun is an HK P2000 LEM in .357 SIG. Uses 12 round mags. The gun came with two. I bought two more when I bought the gun. (Like most HK's, the mags were close to $50 each even back then.)
So when all this chaos really got going, I looked at all my guns and thought about the HK. In all reality, four mags was enough but it's nice to be able to practice and actually eject the mag onto a hard surface without crying. So I thought I would look around for a couple more. As you said, people wanted $100 for them. And only a couple were even for sale. I was looking on gunbroker and noticed a gun store that had ads up for new HK P2000 LEM's in .357 SIG. He only wanted $750 plus $25 shipping. And the gun came with two 12 round mags. I bought one.
So that's the crazy situation we are in. It makes more sense to buy another gun to get more mags! Hey, I've heard for years that you should have an exact duplicate of your CCW gun. In case "something happens" to your primary. I'm not complaining, you can never own too many HK's.