Consider fixing what you have.

When deciding to fix a car I don't look at what it is "worth" used unless repairs approach 25% of the cost if a zero mile car , I look at if the car will be serviceable when fixed and sub 25% of new buys lots of parts.

I tend to buy $ 500 cars with bad engine / trans and think nothing of hanging $ 3,000 in parts on it, ending up with a car that effectively has 35,000 miles and getting another 150,000 easy miles out of it. Sure I could buy a $ 3,500 car that runs but over the next 150,000 miles I'd still be hanging $ 3,000 of parts on it.

The S430 guy sounds like a car guy, that's a plus.