My dog has cancer

I have been battling health problems myself for many years and have lost so much in the recovery. To top if off now my beloved dog Buddy has been diagnosed with cancer and needs the tumor removed, then radiation therapy for around $6000 or his leg amputataed which I can have done at a vet school for $700 to $1000. If possible I'd like him to be able to keep his leg so my goal is $6000 however of course my priority is to keep him around. Because of my own health problems I have not been able to work and do not have the money to keep my dog alive until my own health is recovered. I love my dog and I cannot lose him too. I adopted him from the shelter 3 years ago and he's been my best bud ever since.  He's really helped me through my dark times. He's known for being extremely silly but well behaved.  Absolutely must carry a toy with him where ever he goes and is always in good spirits. Please help me save my dog.