Stray cat in need of medical attention

Mr. Sharp Teeth came over to our house the other night and was crying for help. We were able to take him inside, we did not want to leave him outside due to his injuries and 27 degrees weather. His neck was all bloody and raw on both sides and he was very hungry. Because of the fur you cannot tell how skinny he is, but when you pet him you can feel his ribs poking through. We took him to the vet this morning and the bill came down to ~$1,500 to keep him there for a 10 day observation and treat his wounds. We just want to nurse him back to health so he can be adopted to a new home. We ourselves have 3 cats and are financially unable to care for another cat. We ask that you please help us help this little guy. As little as a couple dollars can go a long way. 
I will provide all the receipts and if there are leftover dollars we will donate to a local shelter!