Tons of good info in the above post, but keep in mind it was written over 10 years ago. Some things have changed with respect to what's available and what to expect. Being from Cleveland myself, I can tell you a couple things to add or perhaps simplify your search.
First, anything north of TN is hugely suspect for cancerous rust, and even southern cars can have issues. BEWARE. Anything south of Kentucky is hugely suspect for sun damage. Also beware.
So about rust. Here is the thing, most people are truly not aware of the insidious rust creeping into their cars. As a result I've had many people swear up and down their cars had no rust but the truth is they had advanced rot, not just a bit of rust, ROT. The problem with unibody cars is that you can't just clean up a bit of surface rust or cut out the bad parts. It doesn't work that way. When corrosion starts to show in some spot, it's generally hidden in many other places. A bubble in the lower rocker panel (behind the ground effects) will also mean that the suspension bolts most likely will not come loose without a torch. So not only do you have rust that body shops will simply refuse to touch, but you have a maintenance nightmare. Just avoid anything with rust.
So how can you tell? Insist on pictures of the underside of the rocker panels and drip rails font to back on both sides of the car. Insist on pictures of the inside edges of bottom of the doors. A general picture from underside of the car will also paint a good picture. Insist on a good clear engine bay shot.
What you are looking for:
- Straight drip rails down the length of the car and no swelling of the seams. If the car has been incorrectly jacked these will be smashed and that's just all bad. It also indicates lack of care in the car's maintenance history. Swelling means the car has cancerous rust. Stay away. Any visible rust is also bad news because what you can see is generally just the tip of the iceberg.
- The doors, usually one side worse than the other, are a bellwether of the car rust exposure. The seams should be 100% clean all the way front to back.
- The engine bay - bare aluminum parts should not oxidized (white). This is a sign of northern humidity and cold. Look for rust creeping around the seams in the metal around the battery box and the top of the shock towers.
Do not accept "garage kept" or "all maintenance performed" as any kind of assurance that the car is good. Most unheated garages are terrible for humidity and often literally destroy a car just sitting there innocently. The top will look great but everything underneath will be destroyed. I've seen this over and over. Low mileage is a great thing in general, but you must know something about how the car was kept. Pictures of the underneath will reveal what has been going on over the years.
That being said, nice worth SC's are definitely available in the $3000-6000 range. If it's cheaper than that it's going to be a headache and will cost you 3x your purchase price by the time you work through all the issues and it will still be a 2nd or 3rd tier car. Find a 1st tier car to start with and enjoy it. These cars really are very reliable and well built. The problem is that 25-30 years and an inadequate maintenance program have often left you with a basket case to figure out.