I found CCI .22 magnum for 15 cents per round with free shipping.
https://www.ammunitiondepot.com/catalog/product/view/id/8372/s/19-cci-maxi-mag-22-wmr-40-grain-jhp/
https://www.ammunitiondepot.com/catalog/product/view/id/8372/s/19-cci-maxi-mag-22-wmr-40-grain-jhp/