At least some armour in the wizarding world is made by goblins, and can be quite valuable.
Hepzibah Smith owned some goblin-made armour, which Voldemort made repeated attempts to purchase from her on behalf of Borgin and Burkes. Their offer went as high as 500 Galleons (HBP20).
According to Phineas Nigellus, goblin-made armour does not require cleaning, because goblins' silver repels mundane dirt, imbibing only that which strengthens it, such as basilisk venom. In this context, "armour" also includes blades such as swords (DH15).
According to Bill Weasley, some Goblins (particularly those that work at Gringotts) believe that wizards have no respect for Goblin ownership. They believe that the true owner of an object is the maker, and not the purchaser. They consider any Goblin-made object bought by a wizard to be rented, and have trouble with the idea of things being passed through generations. They think that when a wizard dies, any Goblin-made objects they 'own' should be retuned to Goblins. (DH25)