I have an interesting question. I was thinking about it a year ago when the es'Hailsat 2 was not launched.
There was an organization called "Outernet" that promissed to broadcast files (including ham radio APRS packets) from geostationary satellites all over the globe.
Then they ran into financial difficulties and their CEO posted that "we're switching to Ka (or Ku?) band, so broadcasting will not be a financial difficulty anymore". So, I started wondering: how can I lease a transponder (probably, a little portion of it) and now much it costs?
I have googled for companies that provide such service and contacted one but they said that I should be a company and sign a NDA to even get the price. (Such a huge price?)
I found an answer that broadcasting company paid \$2M per 37MHz per year. So, 2000000/360/37/1000000*6000= almost \$1 per 6KHz signal per day! So, it's much cheaper than a satellite phone! (6KHz is a SSB bandwitdh *2).
I don't sure they allow to rent this small bandwith, but on the other hand they allowed Outernet to transmit theit narrow unusual signal, so transmitting SSB or FM should be possible. Also in my area ham radio operators should lease a frequency for a repeater or a 24/7 beacon, and AFAIK we even have 0.1 "social importance" price multiplier for "amateur radio beacon" or "amateur radio beacon" radio services. So it should be possible for a private person to rent a frequency and a transponder for ham radio use, but how?