The final sale price probably includes the buyer's premium, that's what auction houses tend to show.
So, who's been checking it out this year for SOHCs? I started looking but ran out of time so far. I had a look for CB400Fs and found 5 in total, last year I paid a bit more attention as I was off work and I even kept notes (nerd alert), there were 2 CB400Fs and 15 CB750s.
This year, the CB400F up tomorrow is a rare 1977 model and does look very nice. I haven't looked at CB750s at all yet, but there are no Rickmans or Seeleys alas.