Edit: Never mind. I missed a part in the Nex guide. Apologies.

Reading fail me thinks. Right above the costs it says:

 

All three sets degrade when used in combat and will eventually need to be repaired similar to barrows items. The items can be repaired by Bob in Lumbridge or using the armour stand in a player owned house for a discount. The cost reduction of using a POH is dependent on your smithing level, up to a 50% discount at 100 smithing (99 with a skillcape boost). The repair costs for Bob are as follows.

 

All the prices u listed are 50% cheaper as the guide says they will be with 99 smithing, there's no need to list this since people are capable of basic math and since cost changes level by level in smithing a singular table of costs would be slightly misleading as it could suggest armour stand cost is universal as shown in table when only glanced at.