This is a difficult question to answer as the time and place of the context is all important. Social status would have great impact on who owned weapons. In many areas, peasants where mere property, especially the further east one goes, they would probably be restricted from owning weapons. While in other regions, there where free men who owed service to nobles, and in some regions such as the Norse lands there were few nobles at all. These later two groups often needing to be armed by law and for defence.
Early medieval military systems often required individuals to equip themselves as appropriate to their status and title. This was set in law by the rulers of each locale and was intended to supply a base of trained troops for military use. This force would be augmented by levies of more common citizens, but this varied greatly from place to place. The Frankish areas for example would have few levied troops while the north would often be mainly levied call ups. But again, time and context are crucial to the definition.
The mandatory ownership of weapons and armor meant that, in order for this system to be effective, people had to be able to afford the armaments they needed to have. The tension between this need and the desire to control the populace was always on the minds of rulers of the period. So while they created laws requiring certain groups to have weapons, they also restricted things thought to be disruptive, such as swords or daggers of a certain length.
One of the examples I bring up when looking at how they viewed the value of swords in the day is the description of the Monk of St Gall quoted below.
“When the kings of the Northmen sent gold and silver as witness of their loyalty and their swords as a mark of their perpetual subjection and surrender, the king gave orders that the precious metals should be thrown upon the floor, and should be looked upon by all with contempt, and be trampled upon by all as though they were dirt. But, as he sat upon his lofty throne, he ordered the swords to be brought to him that he might make trial of them. Then the ambassadors, anxious to avoid the possibility of any suspicion of an evil design, took the swords by the very point (as servants hand knives to their masters) and thus gave them to the emperor at their own risk. He took one by the hilt and tried to bend the tip of the blade right back to the base; but the blade snapped between his hands which were stronger than the iron itself. Then one of the envoys drew his own sword from its sheath and offered it, like a servant, to the emperor's service, saying: "I think you will find this sword as flexible and as strong as your all-conquering right hand could desire." Then the emperor (a true emperor he! As the Prophet Isaiah says in his prophecy, "Consider the rock whence ye were hewn"; for he out of all the vast population of Germany, by the singular favour of God, rose to the level of the strength and courage of an earlier generation) -- the emperor, I say, bent it like a vine-twig from the extreme point back to the hilt, and then let it gradually straighten itself again. Then the envoys gazed upon one another and said in amazement: "Would that our kings held gold and silver so cheap and iron so precious."
Map of Louis the German's domain
Here we see the quality of the piece was recognized, by Louis, and that he held the sword more valuable than the gold and silver tribute brought to him. The importance of kingly gifts in the relationships between rulers, would have set the high end of the market value for swords. Literally the most valuable of treasure.
A major factor that probably affected the price of a sword over the early medieval period was this was also the time of the Danegeld, the huge sums of cash paid to invading forces to request their retreat from aggression. The economic changes this brought to society cannot be ignored. It is estimated the amount of precious metal paid to these marauding armies, based on the chronicles, would not have been less than 22 tons. That's a fair bit of cheddar yo!
This would have altered the markets, trade and prices across the north of Europe in the early medieval period. In the case of swords this would have driven the price down as they were more affordable and in demand.
To answer the original question, the cost of a sword for a lower status soldier was probably the equivalent of a few days or a week’s earnings in relative terms in their context. The upper end of the market was bounded only by the wealth of the given ruler, and how much they wanted to demonstrate their prestige or honor another ruler.
While this leaves many aspects of the economics and social importance of these swords unstated it is a solid answer to say it was driven by the social and economic demands of their time and place and if you were required to have a sword it would have been possible to find one that was attainable, much as it is today.
Sword of St Maurice by Arms & Armor 11th C.
Nathan Clough, Ph.D. is Vice President of Arms and Armor and a member of the governing board of The Oakeshott Institute. He is a historical martial artist and a former university professor of cultural geography. He has given presentations on historical arms at events including Longpoint and Combatcon, and presented scholarly papers at, among others, The International Congress on Medieval Studies.
Craig Johnson is the Production Manager of Arms and Armor and Secretary of The Oakeshott Institute. He has taught and published on the history of arms, armor and western martial arts for over 30 years. He has lectured at several schools and Universities, WMAW, HEMAC, 4W, and ICMS at Kalamazoo. His experiences include iron smelting, jousting, theatrical combat instruction and choreography, historical research, European martial arts and crafting weapons and armor since 1985.