I suspect that the absence of many direct, specific discussions or references to money in Middle-earth arises from the fact that there were no philological quandries concering the words for coins.
Thus, Tolkien didn't have to engage in any "backformation" to create "asterisk"words for money--as Shippey has explained Tolkien's process in
The Road to Middle-earth and
Author of the Century .
Therefore, it just didn't interest him.
