Selling owner's time; popular or niche option ?

[OliveJuice]

Hey all,

While researching Garanteed Income program on some charter companies(or any other similar ownership program), I read about the possibility of selling the owner time you're not able to use during the year.

My question is: is it a popular pratice or is it relatively rare?

I know there are a few sites that advertise owner's time (sailonline.com, traveltalkonline.com and even this very forum) but the offering look very slim. My impression is that not many people sell and/or buy owner's time; am I wrong to think this way?

Thank you all for your time!