I think they are split up amongst the various brand importers around the world to re-sell. If not that, maybe one or several importers make a bid for the karts and then sell them that way.
I recall one chassis importer selling some Grand Finals karts a few years ago. Forgot which brand, and respective importer, that was.
When I left yesterday, Haase had sold 16 or 18 of the karts they brought. They had to return home with 18 of them as they had a temporary import bound for that amount.
As for the OK1, Energy, CRG, Sodi and Praga, I know some customers/drivers were purchasing karts at discounted prices while other packages were purchased by dealers and importers from around the world.