Loathe as I am to ber skeptical of someone, I would understand someone seeking assistance for a sick cat but while end stage liver disease can be fatal, the description here does not sound like it is. And these symptoms can be easily treated. I am not a vet (obviously!) but like many on this site, have much experience caring for cats. A uti often PRECEEDS kidney disease so those two could be together but I just do not think it likely. And many cats - especially those allowed outdoors get fleas. It will not - according to my vet - cost that much for the treatment needed by this kitty. Frankly, this story makes no sense -- both in terms of the costs cited (either they have a really expensive vet - For example: "initial exam, x-ray, and blood work which totalled $500" - that might cost $100 but that's an inflated price if I ever saw one. And there are many differential diagnostics for liver disease or well... I don't know!)
Most of the meds used to stimulate appetite - if one has difficulty with the bills - can be purchased as generics at a pharmacy for not much money. Diazepam for example in generic form is approx $5 for 100 5 mg tabs. (plus whatever fee the pharmacy charges which is anywhere from $1 to $11 here anyway). And why ask for money for surgery that has yet to be performed?
Plus, most vets will allow you to set up a payment plan. I honestly think this web site should be investigated. Unless one asks for the money to go directly to the vet for a specific cat, I have to seriously question it.and showing a picture of a cat and using the cutline "He's going to lie down now. He isn't feeling so well." is beyong exploitive!!
If this kitty is really ill - I suggest you discuss it with your vet and set up payment plans, If you cannot afford it, there are organizations that help very ill cats. IF NOT, then please do not play with people's emotions. I find this very upsetting!