Saving Gretzky's leg

This is little Gretzky, he's about 6 weeks old and was found curled up on the edge of a canal. We took him in and gave him a home and a name and thought he was just a lost little hungry kitten who just needed some food, water and a home. But when we brought him home we noticed his back right leg wasn't working, and in fact it just dragged and dangled with no life at all to it. We were unsure as to what exactly had happened to this poor little guy. He was taken to  the Vet recently with hopes his leg was savable and also to get him up to date on everything he may need. After the vet had gave him a good look over and saw his X-rays we saw that this poor guys leg was broken in 3 places with terrible breaks. The likely result from this may be an Amputation. We have been looking thru vets but after seeing the X-ray and how small he is nobody seems confident in being able to repair and save his leg. Any vet that we been suggested that would have a high chance of being able to save his leg is way past what we can afford. Even if it comes down to it the Amputation Alone is beyond our current ability. We love this little guy and wanna be able to see him be happy and healthy and free of any pain or deformities and we can sure use some help.