Monetary units, now THEY are the bane of researchers! Not only do you need to determine what currency is being used (not always obvious) but to try and get that original price into an understandable 'modern' coomparison. This is best achieved, once the currency is known, by comparing to the average incomes in the country of the currency. This information is about the hardest to come by and only a few examples exist on-line.
UK is as good an example as any with £.s.d. being broken down historically by guinea (£1.05) 20 shillings 240 pennies, 480 half-pennies, 960 farthings, and 1,920 Qu's. Then of course there were third penny coins, groats, (4d) pieces of eight (Spanish currency origin), florins, crowns, half-crowns and slang - tanner, pony, bob, monkey etcetera.
Even more confusing is that the value of a coin was originally based om metal content so the value of a Guinea (Gold coin) was a variable. Fortunately most of glass research is in standardised currency forms.
The tendency in the past to sell glass wholesale by weight was very sensible as it was weight that determined the cost of transport. And of course Adam's example based on volume - which to a certain extent equated to weight. The use of volumetric weight rather than weight or volume alone is still commonly used in pricing transport.