Peter....Not knowing where you live, I can't help much except to add a bit to what Rick said. I can't imagine what else you have wrong that would warrant that much in repair costs unless your 21 came into a serious disagreement with a Kenworth. And let me guess, that's plus shipping and whatever else they "find needing immediate attention."
First, there is a Luthiers Guild that can provide names and numbers close to you. You have an excellent source right here in Mudcat. Lots of guitar pickers who have dealt with repairmen for years. In my little part of the world there are 5 guys I would trust implicitly within a 50 mile radius. Also, some of the supply houses have in-house people that are excellent. True too, there are a number of vintage dealers all over the country that use specific people who are generally top notch. Here's a DON'T for you. DON'T ask your local non-vintage type dealer. They may have someone, but it's not their thing and they will tell you that you get a better job from Martin and the price is worth it and that Rick is wrong...He's NOT!!! I have a friend down in Georgia that sent his D-28 back against advice and wound up with a very "woody" instrument. And Martin whacked him for $835.00 for God knows what!!! That was payable in advance I might add.
Post your general area and someone can help, or send me an e-mail or message and I'll provide you with the numbers and places I mentioned. The 21's were a neat series, don't let yours be a casualty.