Now you know that's not true. It certainly didn't cost me anywhere near that much.
If there are no "Grandmasters" competing, I suspect it has more to do with the nebulous definition of the term, the fact that many (if not most) system that use the title award it based more on a lifetime of contribution to the art than on a specific test (althought tests may well be a part of it) and the fact that if they're competing in the ring, the rank they're looking for is in the ring, not the specific individual arts they may use.