"could anyone ballpark the value for me?"
Apologies for trying to bring more questions than answers.
I feel that in order to ballpark a value you need to take into account some features that impact on price and that includes knowing just what "comparable" means.
As usual around here, I still have no direct answer to my question about whether Old Stamps do have a higher expected value than Intermediate or New Stamps. So I don't know whether you or Drumaholic believe it or not. Do you believe there is a difference in pricing between the eras and it is worth taking it into account in ballparking values?
And I do feel that in order to ballpark a value you need to take condition (keyhole and spider cracks around the mounting hole) into account. But as usual nobody has commented on that either. So I don't know whether you or Drumaholic believe that condition has an influence on ballparking a value, and if so how much. Do you believe that one should take condition into account when ballparking a value? Worth taking into account?
And most of all, I don't know whether your beliefs are backed up by recorded data. Or do you always just check the completed sales and that's enough? I base my beliefs on analysis after recording thousands of sales, and I make the raw data freely available to anybody who questions my interpretation. And that is all part of improving best practice.
I feel like I haven't passed some "old K secret handshake test" and thus nobody is interested in sharing what they know and (as importantly) how they know it. Or have I annoyed you by blathering on too much about science and about trying to improve our practice by being evidence based in our discussions? Am I just in the wrong forum?