The reason that Milner sell Koyo cheaply is simple. I have posted this before. They buy thousands of them. They come by the container load. Milner supply the trade so when you decide not to buy from Milner but Jap Spares Ltd of Wherever town, likely as not they came via Milner. As Carl said to me, some people think we only stock bits for 80s. You should see their warehouse. Like you say, if they are branded, they should be fine. There is no question of them being copies or anything hooky.