Congratulations on your find. I can't add anything on the value. However, I suggest you don't send to TAG. Find a trusted watch person and get a regular service. Prices and quality can vary. I wouldn't recommend walking into a retail shop as the chances are they will just send on to someone else. I would guess you should pay $300-600?? I paid £300 for my last service on a watch but it had a missing part. The good people can sometimes have a significant waiting list. I'm sure someone nearer to your location can recommend someone.
Good luck.