When I quit my job, I paused my Privacy card that was paying for Kagi—but before the renewal date, I realized it was totally worth 2 coffees/month and unpaused. I use it all the time.
Marginal coffees are very different quality and value across individuals making this a poor metric. For yourself, unless you are actually giving up those coffees (which I think is rare among the people who use this phrase) are you really sure that you value it at that rate?
Even as a business, a subscription would be weighed differently to coffee money - you can easily scale the coffees up and down based on how things are going, this is not true with subscriptions, which essentially increase your fixed costs.
Coffees come out of very different mental budget lines to search tools.
