Well, here's my two cents.
For some reason, the ten rounders have always been hard to get. Both my wife and I have 15-22's bought four years or so ago. I wanted 10 round mags so I could shoot from a bench without the long mag getting in the way. I rarely load more than five rounds anyway, a holdover from my bullseye shooting days. For over a year, I could find none...anywhere. Then, three years back, Midway USA had a special and I grabbed a couple...but they were the same size as a 25 round mag but with a blue follower and a pin installed internally to prevent loading more than ten rounds. To say I was upset was putting it mildly...
Maybe six months later, on Midway or CDNN Sports, one of the other online sites, I saw a sale on "shorty" ten round mags so I grabbed a half dozen. My home state was debating magazine capacity laws again...
I haven't seen any for sale since since!