Young Rescue Dog needing dire surgery

Dunkel is a 1 yr old red tick coonhound who was a rescue from Greene County Shelter in Tennessee.  My rescue took Dunkel in before he was going to be put down.  We noticed when he came to Cincinnati that there was something wrong with his back left leg and hip area.  I just took Dunkel to the vet and the news was not good.  This boy had actually been beaten or hit by a car and was never treated for his injury.  Dr. Rush took xrays, and showed me the xrays explaining that since Dunkel's injury had never been treated, blood flow had stopped and there is no ball and socket anymore.  It is just fragmented bones that rub together every time he moves.  There is nothing there to pin either.  The only options at this point is a total hip replacement at Ohio State University at the cost of around $3,000 or an arthroplasty at the cost of 800.00 which is just basically going to clean the area out and give him some pain relief but going this route, he will never walk normal.  This breaks my heart as he is so young, so lovable and is truly a gentle giant.  I would love to give Dunkel the opportunity to get a hip replacement as he likes to walk and since he is so young, he would have a much better chance of being pain free and living a long life!!!  I am in tears as this boy is so gentle and never complains even though he is in a lot of pain.