I have a 39 year old 4.5 qt. KA. It works fine. I don't overload it or try to push it beyond its abilities so the only thing I have had to replace is the flat beater (the coating decided to flake off about 10 years ago.)
This KA is my second one; I bought an even older one- vintage late 30's or early 40's- for $12.00 at an estate auction in the late 60's. It worked fine for about 7 years before I got my "new" one. The old one I gave to a friend and she used it heavily for another 4 or 5 years before it died.
Now, both of mine are/were Hobart made; so I don't know how well the newer non-Hobart ones will hold up. However, I wouldn't be afraid of refurbished/used one if your budget is tight.
For the attachments, the grinder is the one I use regularly. The other stuff just takes up space in my pantry.