I've had an on-off relationship with meditation. I'm not familiar with Calm but have tried Insight Timer, and the main challenge I have is that there are too many options for guided meditations. I found myself spending way more time looking for a meditation than actually meditating, which is not a great feeling. Nowadays I use mindstreaks, and one of the mindstreaks creators, funnily enough, is a product manager at Calm.
Meditation as "getting something for nothing" is an interesting notion. Funny that we think of silence and quiet as "nothing" - to me, they are often everything.