My daugther's cat is very ill and losing weight . :(

[Barkingdog]

My daughter's cat is sick ,he been vomiting and having occasional diarrhea and lost a lot of weight . He went to the vet and she ruled out parasites, diabetes, and thyroid issues . The cat had special food and antacids and he still not getting better . The vet suggested a surgical biopsy b/c she think the cat has an intestinal inflammation condition . My daughter and husband can't afford the surgical biopsy it could cost 2,500-4,000. The cat had blood work but I am not what kind of tests he had. My daughter is going to try steroids and meds and special food and see if that help .
Has anyone had a cat that had an intestinal inflammation condition and how did you treat your cat. I think it's horrible that vet care cost so much money.