Vomiting, quiet cat.

My 5 year old cat starting vomiting on Sunday - a few times and then vomited clear liquid over night on Sunday and on Monday morning - 3-4 times. I took her to the vet yesterday and they ran blood work (kidney failure, etc) and then x-ray for foreign body, etc and both came back fine. Temperature was fine. They kept her for 6 hours, gave her fluids and anti-vomiting drugs and I took her home that night. She hasn't vomited since Monday afternoon (once at the vet - clear liquid). I took her back this morning to the vet for a check up and she was fine on exam and they gave her subcutaneous fluids again. I brought her home she's been resting today - urinated once but isn't interested in food. She's more tired than usual but not totally lethargic. She's a very sensitive cat so the experience of going to the vet could've been rather traumatic for her. The vet is making me very worried and wants her to be hospitalized for days (even though we don't have a diagnosis) and I simply can't afford it. The tests yesterday alone cost $1000. Do you think this is a life threatening event or should I ride it out for a few more days and see how she is? Any insight would be extremely helpful.

Thank you for your quick response! If I bought Beanie in each morning for a dose of subcutaneous fluids for the next couple days, would that also work or does she absolutely need an IV?

Hello again. I am so worried about Beanie. I have no way to get her to a vet tonight - only first thing tomorrow morning. She had IV fluids most of the day yesterday at the vet, the SQ fluids this morning. In theory, will she survive the night until I can get her to the vet tomorrow morning?