I've wanted this product in the past and found the economics to be similarly challenging. [1] Some podcasts already put out professionally created transcriptions which is great, but I'd need to compile them in one place to figure out who said that one direct quote I remember.
Having people transcribe 5 minutes of audio/month in lieu of a subscription cost equal to 3 minutes of professional transcription was one model I had in mind.
I'm also hoping this works out well.