If it were me, I would get a norton 4/8 combo and a barber's hone. That keeps you set for life, plus you can sharpen old blades on the Norton.

Coticules are nice but they are, imo, in the 8K range and leave me wanting more keenness which I can never get no matter how much I try, so I use other stones before it if I want to finish on it.

I don't own the Shapton 30K but it's crazy money, only can be used at the end of the shapton system, etc.