My thoughts:
1) Make the repair completely free of charge (gil or dark matter) for the crafter but make it 'a fee payable to Hydaelyn' that comes out of the person needing repair's pocket. No chance whatsoever of money trading.
2) Repair only to 100%. The crafter is getting nothing out of the transaction so why should the repaired person benefit from the crafter's 'special service'. In effect, the crafter is acting as a temporary 'Mender' NPC.
3) Do not allow the player with broken gear (or better, <25%) to progress past the starting circle until either they repair it themselves, get a fellow team mate to repair it or leave, if none of the previous options are available. There is *zero* point to a player with broken gear doing a dungeon as it negatively affects everyone.
4) Make it so that the player must request the repairs & can only do so during instanced duties.
