In order for you t get the best price on a used car, you will have to check at our consumer ratings as well as supplies that report on reliability and longevity, and applied our own experience and judgment to find out a vehicle's reliability. Read more on http://www.edmunds.com/car-reviews/best-used-cars.html.
They say it pays to shop. Finding the right make and model for you is an idea onto itself that will produce a lot of value. I recommend looking into the geo metro, gas mileage is a big factor for a lot of people. Middlemen are often what increase what you pay, middlemen are car dealerships, avoid middlemen. Buy directly using websites like craigslist.
Keep checking and have a few cars in mind, at a used car lot, keep track of how long they have been there, and then on the last day of the month go in in the evening, ready to buy one of the cars, cash in hand (if possible), and start negotiating say that it has been there for _____ weeks/days, and you are ready to buy tonight for this _______ price. If they don't give you the price you want, just walk out and go somewhere else. The end of the month they will almost always cave they want to hit their targets.
I would buy from a private owner. You can get it financed through your bank or credit union if you qualify. Do a title search with the VIN number and you can do a car history report that will tell you if it has been wrecked or in a flood etc.
Cars go on sale during the release of new models, during this time cars are at the lowest point of price. If you’re looking for a new car this is the best time to buy. Used cars, I suggest you keep an eye out in retirement communities. Older people buy nice cars drive them less and conserve the mileage on their cars. I have often found cars that are nicely priced that have been garage kept, low miles, without defects, in elderly communities. Several different people have different opinions and your answers will vary from one side of the scale to the other. Never buy from friends and family, always take the car to a mechanic for a second opinion (free of charge) don't to give out much information to the mechanic, some will send people to buy the car. Buy current blue book, check to see if the asking price is worth it.