If it has been sitting for 25 years, it needs a master cyl and four calipers, in addition to the aforementioned fluids etc. to get it running.
Let's just say that I decide a late 70s early 80s C3 is a great first car for one of my grandkids. If I am at that auction, and the description includes "running when parked 25 years ago" my max bid is $2000. Maybe less given the flaking paint. It is a crap shoot. Who knows what condition the engine is really in? Who wants to pull the motor? Add $1000 if it were a four speed; just because there are none for sale.
There are decent ones running and driving with decent paint for under $10k. They aren't horrible looking cars. But the rubber bumper is just a reminder that it is from the really sad days of "performance". I know that not every car has to be about performance (hey, I have a 69 1.1 Opel GT, so I get that), but it is a CORVETTE, and sadly it is just a reminder of the middle ages of cars.
https://www.ebay.com/itm/28489756078...gAAOSwJZpicJhv