Does anybody have stats or a general idea on how much metal would have been used to make knights armor, as well as its modern day cost? I am writing a story and am interested on what an armorer might have gone through to create this gear. Any help is greatly appreciated.

You may be interested in these previous answers as well as the linked answer below. I have written a lot about armourers, since they are one of my main fields of study.

Manufacturing and Supplying the Armour of Weapons of a Late Medieval Army
From Ore to Harness: The Steps of Manufacturing Plate Armour
The Importance and Illusiveness of 'Good Steel' in Medieval and Early Modern Armour
Why were Milanese armourers so successful?
The Armour Industry of Milan, contd.
Manufacturing Munition Armour
What did Royal Armour Look Like?
Two Podcast Episodes About the armour industry
The Innovators of Armouring
Commissioning and Customizing Armour
Was medieval armour made from iron or steel?
Could you sue and armourer for malpractice?
How wealthy could an armourer expect to be? Were they considered artists?