Begin maths montage
Lets for now, be generous, say that one block is 1 metre cubed
We already know one Block is two tons, and one block is 300c
This gives us a great start
The only alloy able to come close in terms of weight per m3 while keeping heat resistance ect is a magnesium alloy
The magnesium alloy AZ31 can be around 1-5 USD per kilogram and is commonly used in aerospace engineering.
2032(two tons) times $3 is $9096
So then one armour block is $9096
But wait!
How tall is a human... two metres (average), well then
One block is at least 2m high, which would put it at $18192 per block, while also being magic and weighing less than it should.
Going off of the first result, we get the conversion:
300c or $9096
1c = $30.32
$1 = 0.03c
I'm definitely wrong, so feel free to tell me I'm an idiot, so now we can all laugh at my stupidity
Any other theories are probably better than this.