Why is the vet so expensive?

Disclaimer- If you're not interested in my cat, don't read this.

Yesterday, I noticed Max (the cat) had a wet spot on his side. Since he is an outdoor cat and prone to the elements, I assumed he had either gotten wet or been licking himself in that spot. I couldn't get a good look, so I just figured I'd check back later. This morning, I was sitting at the kitchen table gazing out at the wreck of toys and chairs and brooms and rakes that is our courtyard, and Max wandered by the door. I almost threw up. On his side, he had licked off all the hair in a circle the size of my palm and there I could see some horrific looking wound. Upon closer inspection, I noticed a rather large puncture wound, and there was some sort of bruise or blood on the skin. It looked like there may be another puncture wound, but I could not look at it long enough to tell. So then I am anxious. I don't know why, I mean, he has had wounds before, and they have healed. I just don't know how I am going to take him to the vet when I have two small children, and I am late for playgroup, but isn't this more important, and what should I do? So, I consult with my neighbor who says maybe someone shot him with a beebe gun (Aack! Why? He is the sweetest most harmless cat ever!) And I decide I will try to find a sitter during nap time and take him to the vet. Well, nap time rolls around, of course, I can't find a sitter. (What, no one is free for a few hours in the middle of the workday? What happened to all the college students I used to know?) In the meantime, I return home from playgroup, put Ceci down for her nap, venture into "the shed of no return" to retrieve the very dirty cat carrier, and hose that mother off. I eventually put Henry down for a nap and do some dishes. (I know, you are marvelling at the excitement that is my life. "How can she handle such a thrilling afternoon?" you are saying. "She must be exhausted!" This is why I take a nap.) But I am too anxious to sleep. So after they wake up, Ceci, Henry, and I get Max and go to the vet. But first I must get Max into the cat carrier. Have you ever tried to do this? To put a cat in a cat carrier? It is a two person job. But I was going at it alone. As a pregnant woman, I am not even supposed to be handling cats. Well, after much rescruffing of his neck and repositioning of his hind legs, I eventually get him in there, and he meows the whole way to the vet. Henry and Ceci comforted him, though. "It's okay, Max. You'll be okay. We're just going for a ride"...etc. It was SO cute. It turns out Max was in a fight, or rather, jumped because you and I both know Max is a lover, not a fighter. He is on antibiotics and slated to make a full recovery. However, during the exam, the doctor heard a heart murmur. This most likely means he has an overactive thyroid (which explains his constant eating and minimal weight gain), but to determine this as fact, we have to get him $130 worth of blood tests (!!!). Then he will have to go on twice daily doses of medicine. Or he can get radiation (!!!) treatment. But that is expensive (as if daily medicine is not). I can't believe this. We haven't even brought Stella in yet for her visit. Ignorance is bliss.
All this, and on the way home...my check engine light came on.
Sigh.