Hi Mike, and welcome to the forum. The first thing you should probably do is update your profile to include your location. People appreciate it, it's relevant to your search, and it's the rules.
Most important? Depends...
Location is important to the cat you buy, as they can be expensive to transport (like a car, etc.).
Condition of the cat v. price may depend on whether you want one ready-to-go or are willing to make repairs. The cats you mentioned use many common automotive drive train parts, so have similar issues to look (out) for. Are you capable mechanically?
Features vary, such as flat-bed, fully enclosed passenger van-style, plow blade, etc., depending on your intended use. Many folks modify them as needed, but that's extra work. What are you looking for? What do you want to do with it?
I'd guess a nice clean cat might run 8-14k$. ???? Best bet for learning about cats would be either reading more here or find someone with a cat and have them teach you a bit about 'em.