Maybe other members can advise. UK prices seem higher than some other countries. US is the place to buy any early Honda which seem to see less mileage than say UK EU Australia. The early framed bikes have many desirable sandcast items fitted but by about frame 20000 the fitments became more close to K1s This is why the early diecast bikes are in higher demand. I suspect a good K0 in the 10k to 20k frame range can be had for US$10K, sometimes a bit less and of course much higher for low good low numbered framed examples
One thing is for sure and you will need to be aware of this, the China virus pandemic will most definitely have a major impact on prices. Others may think not but it's already having that impact now.