I got the same shock yesterday when I tried to find 22 ammo to squirrel hunt with. None at Walmart, Gander mountain or any of the on line places like Cabella's, Bass Pro or Midway.
I did find some CCI green tag sub sonic target loads at a small town gun shop. No one wanted them, they were pricey but not marked up. Turned out I was looking for target loads as my Rem 541S loves them. My rifle will put three in about a 3/8" group at 50 yds, if I do my part the squirrels don't stand a chance.