2022 update:
When renewing my plan recently, I saw that
Red Pocket now offers a
$30/year plan (2.50/month) that comes with 200 minutes, 1000 SMS and 200MB of 4G data per month.This is only available on the T-Mobile network and you get unlimited "2G" data @128kbps after exhausting that allotment. Things like airline apps or google maps navigation might be slow as molasses, but continue to work.
I believe this to be the cheapest long-term-expiration 'normal' SIM card/number currently on the market..