I would more or less agree with those figures, except for the Highest Possible. So in a private sale:

Abas Major: £700 + (higher for wood grip) - assuming excellent condition
Tell II: £120-150 - assuming excellent condition
Acvoke: £180 - 220 - assuming excellent condition
Highest Possible: £700 - if it is only the bluing that has worn off and there is no pitting, and the lettering is still sharp. More for the earlier smooth horn grip version.

Cheers,
John