For instance, in late 1970s' Poland, one trofa consisted of 400 g of rye bread, 100 g of wheat flour, 250 g of potatoes, 100 g of beef, 100 g of sugar, 80 g of butter, and 1/2 litre of milk. Assuming that its content has not changed, you take the cost of the food (8.70 PLN in 2016), add 20% for condiments and preparation, and get 10.50 PLN as the 2016 price of a trofa in Poland.[0]
In Octavian's times, one denarius could buy you 2 trofas (with content appropriate for ancient Mediterranean lands),[0] Judas's 30 pieces of silver were worth 60 trofas,[1] etc.
Unfortunately, Żabiński published in Polish behind the Iron Curtain so the trofa is virtually unknown outside Poland. The Big Mac index is its pale reflection.
More information in Polish:
[0] A table of trofa's price from Octavian's Rome to contemporary Poland: http://blognumizmatyczny.pl/2016/03/14/trofa-miernik-wartosc...
[1] Thirty pieces of silver: http://bazhum.muzhp.pl/media//files/Collectanea_Theologica/C...
[2] The purchasing power in medieval Balkans: https://repozytorium.amu.edu.pl/bitstream/10593/8080/1/11_Zb...
[3] Google search: https://www.google.com/search?q=Żabiński+trofa