It failed inspection because of these reasons

We don't get involved with costs here because there's way too many variables. You can spend 20 bucks or 40 bucks for one ball joint. Who is going to do the work, a professional you pay by the hour or you? What is the shop's labor rate if you're taking it to a mechanic?

A single exhaust part is usually next to impossible to replace without damaging the parts it connects to, so you'll usually end up with more in parts than you expected. Is that pipe welded on and will have to be cut off, or is it clamped on and will have to be cut off, then the creases stretched out before new parts can be installed? Any repair shop should be able to inspect your car, then give you a pretty close written estimate.