I believe it`s due to them being made in new zealand or aussie, can`t recall which, but RHS bought out the pro topline company. I ordered a set of RHS vortec heads, bare castings, they are very heavy casted, they assembled without any problems, the surfaces were flat and true, and there performance is on target. I gave $450 for the pair. I couldn`t ask for any better.
I believe that when RHS purchased pro-topline they had some quality issues for a while but I believe most of these have been resolved. I would make sure that they are new stock and not discontinued or old heads possibly from when they first bought pro-topline. I personally am a little leary of the austrailian companies. I've seen a lot of junk rocker arms from these companies and have heard a few horror stories. RHS went out of business for a long time but was resurrected by compcams a few years back. They use to do good work but have not heard a lot about them since starting back up.
I purchased a set of the 200cc alum heads and the castings to me look very nice I havent assembled them yet. but dont look like there needs to be anything done to them out of the box. I am sure that improvements could be made but for as cast they are nice.