Please can you help this little guy!

This little fella has adopted us as he has been abandoned and nowhere to go. He was sleeping in my garage and very scared until he slowly had the courage to come and eat some biscuit's. He is really cute and very loving. He didn't look in good health so I took him to the vet to be checked up and they found he was micro-chipped and his name is Claude. I spoke with the owner and he wants nothing to do with him after telling him that he needs urgent dental treatment for rotten teeth ($800). It would be sad to just put him down (which is what the previous owner suggested) and we really don't want to have to do so. We would be most grateful for any contribution that can help us pay for his dental treatment so he can live a happy life as he is around 8 years old. Thank you!