JC: do we have any more precise references other than the credit at the end? as it stands, it is very difficult to fact check and compare. In my own search I have found period references giving very different values, and there seem to be a significant regional variation depending on availability. The Regia pages also have a list, which is again different https://regia.org/research/misc/costs.htm
Sandra: I can put you in direct contact with Caroline Buckley to discuss, if you want - the section from 'currency' onwards I took it from a document she write some years ago, I think when she did her degree in archaeology at the same time/place as Trix. By all means change/update or point out regional differences, as appropriate.
JC: I don't have enough of an overview yet to make changes, that is why I am looking for the references to understand where the differences arise from. If you can get me in contact Caroline that would be great.