They have quite a few for sale... with some saying "lunchtime special" which was something that was appearing at the time of those first Reissues - allegedly from the factory, but done by staff outside of the normal production run.
I think some of those he's listed are KOs, but most are probably "legit" from the factory, as I think some of those moulds haven't been KOed (Hot Rod & Astrotrain?).

This person is in Holland, so if these really are "lunchtime specials", he must have been amassing a serious collection of them at the time (about 10 years ago now).
But with so many KOs out there now, these unauthorised figures don't have much value in them. Before KOs started rearing their heads, a (verified) prototype would have been a valuable part of Transformers History.... now though, there's too much risk that it is just a fake for it to be worth buying, or claiming that you have one.

Prototypes with any potential value are the ones that can be verified as prototypes, by having a destroyed face and/or "not for sale" etched into them somewhere. (but yeah, you could do that to a KO and pass it off as a prototype... so it just isn't worth spending excessive money on something that could be a fake, and doesn't look very nice anyway)