A very low-mileage Audi V8 Quattro is up on eBay with 20 days left at a Buy-It-Now or Best Offer price of $6500. This was the predecessor to the A8, offering a 3.6L 247hp V8. Weak by today’s standards, but not too shabby in 1990. It was also the only full-size sedan with AWD at time and came with a galvanized body, so rust shouldn’t be a problem.
I think the big selling point here is the extremely low 41k miles. It’s no Ur-S4 or S6, but $6500 for a fun, big AWD sedan is not too bad at all.