On the Microsoft website, if you go to your Game Pass Ultimate subscription and turn on recurring billing, you can select a plan for $0.05/day, which works out to $18.25/year.
Note: If you don't already have Game Pass Ultimate, use the 3 months for $1 promotion to sign up, than turn on recurring billing using the $0.05/day option.
Here is the original Reddit thread on it:
Edit: kidrocklive says his email included the verbiage "We'll email you ahead of time if that price ever changes." (Mine did not.) Be prepared to cancel if Microsoft ups the price.
Edit 2: People on Reddit and SD are reporting not seeing the $0.05 option anymore. Might be dead.