I went into CarMax to get my car appraised, after hearing the good experience of others. I went there around 11 am, walked in without an appointment, and was promptly greeted by George Ter-Oganov, who also gave us the rundown on how it works. The whole process takes about 30-45 minutes, they have their experts take a look at the car, and give you a print out of what the car is worth based on it's condition.
What makes this place different than other dealerships is that they don't act like vultures. They let you do your own thing, they don't persuade you to buy from them, and you don't feel rushed. The atmosphere is very approachable and the sales consultants are willing to help and offer advice for buying cars.
Car appraisals are good for 7 days. My only complaint is that they don't sell any new cars, but they offer really good deals for the used cars they have on their lot. If you're looking to buy a used car and don't want someone breathing down your neck, give CarMax a shot. They're the real deal!