Also, if you buy a really good one for $20K, it will still be worth $20K or more forever. Pelicanparts.com forums are a great source.
If I had a 2 car garage, I would still have my 84' 911 (for life).
They are also achingly beautiful.
I'm unconvinced you need a more modern Porsche. If you really need strong A/C, get a 964 (89-92'), but that means more complexity. I think the sweet spot is 84-88'.