In the wholesale world, an '04 Cavalier with decent miles is a $1000 car. They are worthless, always have been, always will be. If you were going to drive it into the ground then it doesn't matter, but if you want something that holds its value to a degree, avoid those things. Value depends on demand, so you need to pick something that people actively seek out - I mean I like Saturns, but how many people that just need a car get up in the morning and search for an SL1 on Craigslist? Stick with a Honda or a Toyota if you want it to retain any value at all.
And the older/cheaper the car, the less the KBB etc matters. The numbers get screwy in the value guides after 6 or 7 model years as they are based on transactions, and as cars age the number of transactions drop, so an anomaly in either direction on the price for one transaction messes up the average. But more important than that, once a car gets to be that old or older, the value is in the condition and mileage, not anything else. The "book" might say to add say $400 for "low mileage/extra clean", but in reality, a 2004 Civic with 40,000 miles is worth WAY more than a 2004 Civic with 140,000 miles.
If you can find a really low mile, clean example of something, pay more for it, it will always be worth more when you resell it as the number of comparables to it in the market will have dropped. I had a mint '98 Tracker 4 door, super low miles, all the right options, good colour combo, last year of the body style, it was THE Tracker you'd want if you wanted a Tracker. You couldn't find that truck again if you wanted to. I wanted a lot of money for it, and some guy looked at it and broke out the "book value" pages he had printed off the internet to show me my price was too high. "So buy one from the book" I told him. "Well, the book doesn't sell cars." he said. "Exactly". My opinion is free so take it for what it's worth, but if you want to buy a cheaper car and have it maintain its value, pay more for a nice one, then by the time you are done with it it's still worth what an average one is worth. And not $1000 like a Cavalier ha ha.
