Please help us save Hulusi the cat!

Hulusi is a 6 month old cat in Istanbul, who was abandoned by his previous owner about two months ago. He had to live on the streets for a month, but since he is not used to living outdoors, he got sick pretty quickly. I found him a foster home and took him to a vet clinic. He had wounds in his mouth and he had to get a shot of antibiotics everyday for a week. After a week, his wounds seemed better, so we stopped the antibiotics treatment and switched to a mouth spray. It's been two weeks and unfortunately his mouth wounds are acting up again. The vet said that his illness is called ''juvenile periodontitis'' and ''mucositis''. We took him to 3 different vets and they all said that all his teeth must be pulled out. The whole operation will cost around 600-650 dollars, which I do not have. I am still a student and I do not have a stable income, so it is impossible for me to afford this operation. If Hulusi does not get a treatment, the wounds will continue spreading and he will lose his whole mouth... I am so desperate, I know I have to save him but I do not have the necessary funds. Please help me save Hulusi, he is an amazing cat with so much love and affection!