$2.50/Mo Red Pocket Prepaid Plan: 200 Talk 1000 Text 200MB – $30

Reposting for visibility, as searching for ‘SIM’ on SL doesn’t show this unless you go many pages deep.
It’s an MVNO that can work on the T-Mobile or Sprint network
$2.50 a month or $30 year for a backup, ghost, emergency, or kids phone is the absolute cheapest I can find in the US
https://www.ebay.com/itm/133196831828