That's a really in depth question. Knights were around for a very long time, the types of weapons used by and against them changed and varied drastically over this time. They would have started out with swords of varying sizes/styles but as plate armour improved swords became less effective so war hammers became more common as they could crush and pierce armour. There were many different kinds of war hammer too, they were constantly evolving. And also pikes were used against cavalry, so not necessarily by knights themselves. You had flails and maces too, though less common, they were also able to pierce and crush plate armour. Daggers would also have been common, but not as a main weapon obviously. The [Miserichorde](http://en.wikipedia.org/wiki/Misericorde_(weapon)) was used to finish off mortally wounded knights or in close quarter grappling, which was surprisingly common.

As for putting a USD on any of them? That's a really tricky one. To have armour you would have to have it made for you, personally. That would more than likely mean having a personal armourer, apprentice, the forge for them to work in and the resources to accommodate all of that. You would likely also be deploying your own troops, so some of them will need to be armoured too. It's not like you'd nip down to the local armour dealer and pay him for a floor model and that was that, off you go like buying a car today. Though it would have been possible to order armour from someone you don't employ full time, most of the time it wouldn't just be the cost of the armour or the sword, but also the infrastructure to manufacture it all. Armies were a collection of nobles and the troops they could muster coming under someone's banner, usually a king or claimant to a throne.

There might be sources that could quantify how much an individual item might cost, which could be roughly translated in an average wage, but I'm not aware of any.

So the cost of being able to manufacture armour and weapons would be roughly the cost of at least one highly skilled labourer, equivalent to say an engineer's wages today, maybe $200k per annum employed full time to maintain and repair armour too. As well as being able to support the purchase or acquiring of the raw materials. I don't really know how to put a price on that, you might even have to mine the ore from your own land and employ and support the people doing it, the equivalent of many thousands more.

Basically the cost of the suit of armour itself would pale in comparison to the cost of manufacturing it. It's more like owning a NASCAR or sports team in terms of cost than anything else I can think of.

I am woefully unqualified to do conversions from medieval costs to modern costs so I can't give you figures in USD but I did write a post a little while ago about the cost of a knight's equipment in the 12th-13th centuries. Actual costs varied a lot across the course of the Middle Ages so you can't really take one figure and apply it everywhere.

Short answer:

N. Denholm Young gives the total cost to equip a knight in the twelfth century as £5 but that cost went up significantly in later centuries. By the thirteenth century a war horse could cost between £20 and £100 while the cost of equipment had risen to between £25 and £50.

The average pay for a day laborer at that time was between 1.5d. and 2d. while skilled craftsmen made more like 4d. a day. There were 240d. (-ish, 240 is the figure for pre-decimal modern English currency you can expect medieval conversions to have been more fliud) in £1. So in the twelfth century the cost was about equivalent to a years wage for a skilled worker or two years for a day laborer. This rose drastically as time went on.

Longer answer can be read [here] (http://www.reddit.com/r/AskHistorians/comments/26nuj9/how_expensive_were_medieval_weapons_and_armor/chszg38)

EDIT SINCE i HAVE ACCESS TO MY LIBRARY NOW, i CAN GIVE MUCH MORE IN DEPTH ANSWER

take note, that in effort to make the prices layman-accessible, Im translating prices in 1400'ies marks and grosses, as well as barter prices in cows/sheep (approx worth 40 and 4 grosses each) into polish zloty, and then polish zloty into dollars. For simplicity sake, I round up 1 gross=33 modern polish zloty=11 dollars.

So (depending on quality, from lowest recorded to highest recorded price XIII-XV century):

                ** In grosses / dollars**

Plate cuirras : 24 grosses / 264$

frock-plate/smallplate: 192 grosses /2112$

Full plate suit: 480-576 grosses/ 5280-6336$

chainmail: 96 grosses (cheapest short shirt of mail) / 1056$

arm/leg plates: 10-120 grosses / 110-1320$

capalin helmet: 30 grosses/ 330$

Sallate helmet: 60 grosses / 660$

shield: 7-90 grosses / 77-990$

kord, saber: 8-36 / 88-396$

sword: 32 (cheapest) 120 (good quality) 240 (very good quality, gilded) / 352-1320-2640$ (ceremonial swords might be worth up to 20 000$, and executioner swords varied wildly in price, as there was a considerably smaller market for those)

bow: 24 grosses/ 264$

crossbow: 48-60grosses/ 528-660$

lance: 15-21grosses / 165-231$

pike/spear/cheap glaive: 6 grosses/ 66$

Horse: 96(farmhorse) -480(good quality strider) 720 (imported stallion, quality breed foaling mare) / 1056-7920$

spurrs: 4-15 grosses/ 44-165$

quiver full of arrows: 8 grosses / 88$

medieval smoothbore gun: 60 grosses / 660$

TOTAL in medieval polish marks/dollars

Infantryman: 0.75-3 marks / 393.33 $ - 1570 $

Archer/crossbowman: 7-24 marks / 3666 $ - 12563$

rider/knight: 25-53 marks / 13086 $ - 27743$

Average yearly income for a noble/knight (note: these percentages apply only to the upper feudal caste and does not represent the entire society):

11% - 30 marks a year / 14400$ (hedge, retainer)

18% - 60 marks a year /28800$ (landed knight)

11% - aprox 900 marks a year / 432000$ (entitled nobleman)

7% - up to 6000 marks a year /2880000$ (a voivod or a prince)

the rest: aprox: 1500 marks a year /720000$ (depending on the office/possition held)

SOurces:

Szymczak J. Koszt i produkcja uzbrojenia rycerskiego, XIII-XV wiek (cost and production of medieval knightly equipment)

Nowakowski A. "Uzbrojenie w Polsce średniowiecznej 1450-1500"(armaments of medieval Poland 1450-1500)

Nowakowski A. "O wojskach Zakonu Krzyżackiego" (on the army of the Teutonic order: sub-chapter on ordered shipments of arms and armor)

Kuczyński S.M., "Wielka Wojna z Zakonem Krzyżackim", (great war on the teutonic order: sub-chapter on Polish and Teutonc armouries)

"Rekordy miejske miasta Torunia 1350-1600" (public records of the city of Torun, bills and spending records on guard equipment, defense and the armoury).