My JOC cost me around £400 as I took one of the last minute deals available from a provider who had someone drop out a couple of weeks before the start date. It took 1 day, it was 4 hours of theory and 4 hours in the sim. As I say I am not convinced about the course at all but I was aware that some operators looked for it and I did it on that basis. I don't think it would generally help in the sim assessment because the JOC looked at the more extreme parts of the typical jet aircraft flight envelope, whereas most sim assessments are based around a standard flight profile condensed with an abnormality/emergency thrown in, I don't think it's normal for them to have you do steep turns and stalls at FL390 which was something we did in the JOC to see how the aircraft reacts differently at altitude etc.