I get the impression that proper weaponry and armor were expensive in the middle ages. If that is so, which one was more expensive? Were you more likely to have a sword or other real weapon or some ringmail?

Armor was way more expensive because it was a lot more time-intensive, especially chainmail. Especially more early in the Middle Ages, a lot of soldiers got by with helmet, shield, and weapon. 

As for what kind of weapon, the most “common”” weapons were based on things that farmers might actually own – the spear and a lot of polearms were basically Bladed Tool I Own on a Stick, axes that were normally used to cut down trees or chop firewood getting pressed into service in war. 

But swords were not uncommon either. They were something of a luxury item, since they were only used for war, but archaeologists keep turning up large numbers of them.