average price for rays seems to be around £450 some for less some for more. at the end of the day its what people are willing to pay. i think you'll struggle at £600
and rich the O40's aren't useless,
in the dry on a track you'll struggle to find a tyre to match it, and although they aren't great in the wet they are still very progressive. i didn't mind them, but there are better alround tyres out there.