Barbossa was brought back to free Tia Dalma, not to rescue Jack Sparrow. Tia Dalma was actually in the process of reviving Barbossa when Jack showed up and traded the cursed monkey for a jar of dirt to ward off Davy Jones. Jack had not finished in Davy Jones's Locker yet when she started to revive Barbossa. This could also be Tia Dalma's reason for helping the others rescue Jack without charging them.