Depending on where you live, look for a private party selling a used Caddy. I got my '02 SDV (mentioned above) in 2002 for $4300 with 80K miles on it, put on a good set of tires, and have spent very little on maintenance since. It's in outstanding shape. I say "depending on where you live," since some regions have better offerings than others. New England is excellent. New Jersey sucks.
Find a used Caddy from a state where salt is not extensively used on winter roads. You'll be much happier..
You bought an 02 Caddy for $4300 in 02? Man, it sounds like you stole that car. Or maybe you left out a "0" when you typed that price?
Anyway, I really don't need a big car anymore. When I traveled on the road 60,000-80,000 miles a year in my sales job I bought Cadillacs, and later on Mercury Grand Marquis, because I wanted the comfort and safety of a large heavy car. Now I only put 12-15K a year on a car for local driving, and if we take a long trip we usually fly or rent a bigger car.