Any broken item may be repaired by a qualified weaponsmith at a cost based upon the formula below. Depending on the situation, a smith may set the price above or below the base cost.
Base repair cost: (Item cost) x (item level) x (10%), maximum of 100% item cost
This way, heroic tier items may be repaired for a bit less than purchasing them new, but once you approach paragon tier items they are at a high enough level that repairing them is just as difficult as making one.
Additionally, I would be happy to let someone try to repair a weapon themselves, provided they spent a feat to become a “smith.” Off of the top of my head, it could look something like this:
- Requirements: trained in athletics (to work with metal) and arcana (knowledge of magic items); warhammer weapon focus (to approximate training as a smith)
- Repair Item: During an extended rest, attempt to repair an item.
- Hard DC + item level (As level 3 characters, a “hard” DC is 20)
- Bonus to your roll = athletics bonus + arcana bonus
Again, becoming a smith is totally optional, and these rules are a first draft.