Help Cheerio Walk Normally Again

Hi everyone!! Most of you already know, I have a dog named Cheerio. He recently suffered a fall and his two hind legs have suffered an injury. Currently, he cannot walk with his two hind legs and the vet has quoted a large amount of money to which I currently not available at the moment. The MRIs / X-rays are quoted to be at $5,000+ (which is pretty steep).