Are you talking about buying 'live' sand thats bagged from a fish store, or just that live sand does or does not exist?
I think that spending crazy money on 'Live' sand that's bagged months before you buy it, transported in non temperature controlled trucks, set out in the sun on pallets, etc is not something I would ever put in an established tank. I might use it on a new tank, but only because it is going to be full of gunk that would probably kickstart a cycle pretty well.
I've only ever bought dry sand, and used seed sand from established tanks to set up my sytems. Since I've only used this method, or purchased established tanks, I've never actually experienced the waiting for a tank to cycle myself.