[Low Tech]Cost of armour and TL

[Agramer]

In Fantasy world which is on average TL2-3,but has Plate armour from TL4(Knights in shining armour syndrome),what should be progression in costs of higher TL armour?

If TL2 Armour prices are as listed,what modifier to cost should TL3 and TL4 armours get?

Same question for weapons.

Thanks