A Buck "Special" model 119 is a classic that's pretty inexpensive. 6" blade and while it may be $81 at the Buck website, it's closer to about $40 at Walmart last I checked.
I've never gotten into a knife fight with a cat with mine, but it has done most other work pretty well. Fairly sure the blade is sturdy enough to slice a cat's neck if I pressed it into service as such.
I remember sleeping in my tent up in Washington in my pre-gun owning days, and having a big cat trip over the guy wire to my pup tent. It screamed at me while the walls of the tent shook, and I damn near wet myself. I got out my 3" swiss army knife and realized exactly how screwed I was. Woke up the next morning and found 3" wide cat tracks around my tent.
Got a big knife that same week once I was back in town, though what I got was a knockoff Tanto blade. Probably would have been fine for stabbing kitty, but not very useful for anything else. Sucked as a fishing or utility knife outdoors.