I know I am also new here, but I hope y'all won't mind if I say something in regard to this message.
I am so sorry for you and your dog. As I was reading your message, it brought so many memories for me. As responsible and loving pet owners, we all have struggled with this dificult desision at some time or another and it is always heart wrenching.
As an animal owner and a former vet tech, I've been on both sides of the table. I've held my own pets and cried as they were euthanized, but I've also held many other's pets and cried right along with them, feeling their owners pain. I've had to euthanize entire litters of puppies and kittens as soon as they have come into the world, simply because their owners didn't have their pets neutered and the babies were unwanted. These are the ones that hurt the most! As a pet sitter, I've taken my client's animals to be euthanized and even if the pet is not my own, it's certainly no easier for me. Some of my clients can make the decision, but are incapable of walking into the vet clinic because they are so overwrought with grief.
As others have said, you know your dog better than anyone else. Is she in pain and does she seem to enjoy her life. Does she still eat? Does her deteriating hips prevent her from walking or just some mild discomfort? You have to weigh the good with the bad. Talk to your veterinarian and discuss her prognoisis. If he/she says, "you know, I think we've done everything for this dog and even if we proceed with the surgery, her quality of life is not going to be good", maybe putting her down is the best option. Is the overriding consideration the cost of the surgery? Although, I've not worked in a vet clinic for several years, $2000.00 seems a little steep for the procedure your dog requires. (at least in my area) Maybe there is a program in your area for those who can't afford expensive treatments for their pets. I know in my area, there are some vets who are willing to do some treatments at cost. Some vets will set up payment plans to help ease the financial burden.
My heart goes out to you. Listen to your dog and listen to your own heart and when you come to your decision, trust in yourself and believe that you've made the right decision for both you and your dog. Rememember, euthansia is the final act of love and compassion that you can show to your dog, to ease her suffering at the expense of your own is a very kind and unselfish act. Also know that you have been kind to her in life and because of you she had many years of love and happiness.
Again, I know we all feel your pain at making this decision. What ever you decide, let us know and also know that we are here if you need to talk.