In pre-modern times it was common to make war pay for itself. One way was to exact ransom from prisoners-of-war. The ransom for Jean II, captured at Poitiers, was so enormous (up in the hundreds of millions of ducats by game reckoning, that the French never actually paid it, the king died in regal captivity in England before the sum could be collected.)

Item                    Number                  Ducats                  Captor                  

M. de Corpe             1                       220,000                 two men-at-arms and     

                                                                        an archer               

Man-at-arms             1                       8,000                   Sir Robert Laurence     

Man-at-arms             1                       8,000                    Sir Robert Laurence    

Man-at-arms                                     16,000                  Unknown                 

Man-at-arms             1                       3,000                   a man-at-arms           

Man-at-arms             1                       650                     an archer               

Unknown                 1                       360                      an archer
              

In terms of HYW, the Players are at the level of the Seigneur de Corpe or higher. Family members would presumably be at rather less than what the Player would have to pay. Most NPCs would be at the level of the men-at-arms, the precise amount presumably varying with the status and skills of the NPC.

Amounts apparently varied according to the rank of the captor as well.

Although these figures are for a great many years later than 1337, there was little inflation during the period.