Nose pads are a consumable item in glasses. Standard pads are silicone which are extremely comfortable but also soft and don't last a very long time. Hard plastic is durable but conforms to your nose less. Titanium ones will probably outlast you but need to be perfectly adjusted to be comfortable.
They are priced per pair as it makes sense to change both so they look the same. If you find this to be beyond the pale then we'll sell you one on request.