Most people hate the car buying process. As humans, most of us have a fear of missing out. This worry becomes especially poignant when purchasing a new vehicle, and many buyers have a constant stress that they didn't haggle far enough, or left a significant amount of money on the table.
Personally, I love everything about the car buying process. The hunt, the research, and the negotiations over price. If there was a job where the entire work load consisted of shopping for other peoples' cars, I'd take it in an instant. I've also bought my fair share of vehicles over the years, and although I have a bias, I think it's fair to say that they all came as very good deals.
For those that aren't loonies like me, hopefully this guide will help you ease the pain of the entire negotiating experience.
For "Mostly New" Vehicles
There are two ways to approach purchasing a used vehicle, and that means two different strategies. If you are going after what I like to call a "mostly new" automobile, then this is the way I recommend you approach it. This would be for cars that are either certified-pre-owned (CPO) and maybe 3-5 years old. New enough that there is still some semblance of a warranty.
Shop Around- If you are going after something that is still mostly new, then it is going to be sitting around on dealer lots, not Craigslist or more shady used car dealers. This means you should around heavily. Look at vehicles on lots that are 300 miles away from your house. Even if you aren't willing to drive that far, you want to make it apparent to the dealership that you would go that much out of your way for the right deal.
Research Market Values- New vehicles have tons of information about them and their going rates all over the web, so simply do a few Google searches and see what you can come up with. You can also check KBB and NADA values, but remember that those prices are just guides and will vary from area to area. If you live in southern California, you can bet sports cars will cheaper in Vermont during the middle of January. That's just the nature of the game.
CarFax- I am actually not a big fan of CarFax, as I will explain further in the cheap used car section below. While it is a good tool, and certainly something that should be referenced when making a $20,000+ purchase, most people place WAY too much emphasis on them. CarFax reports will miss all of the time, and are only important for showing accident records.
THIS MEANS THEY HAVE ZERO INDICATION OF RELIABILITY. You can have an automobile that's been abused and beaten to an inch of its life mechanically, but was never in an accident. For whatever reason, there is a large group of people that would look at this car, see a clean CarFax, and think it is a good choice to buy.
Any vehicle you are buying that is somewhat new should have a clean CarFax. If there is anything fishy there, move along. But that tells you nothing about how the car was cared for. For that, you want to move on to...
Service Records- Any vehicle that you are buying this new should have full service records. Every single oil change should be documented. If the car doesn't come with these, I don't care how much you like it, or what lies the dealer tells you- MOVE ALONG. When you are spending $2000 on a car, you shouldn't expect full records and details of maintenance. When you are spending $20,000 on a CPO or similarly "mostly new" vehicle you should DEMAND all service records.
For Really Cheap Used Cars
Believe it or not, it's much harder to buy a cheap used car. When you are shopping for "mostly new" cars you will find plenty of well-cared for examples, and if the dealer you are at doesn't have any, you just move to the dealer across down.
For super cheap, and by that I mean approximately $5000 or less, there are a lot of potential mistakes to be made, and you want to avoid buying a lemon used car. These are the things you want to focus on for negotiating price on a car this cheap.
Test Every Feature- I don't care if you never plan to use the cassette deck. I don't care if you never have people in the backseat who will use the rear interior lights or "pop-out" cup holders. Look over the car you are buying and press EVERY button. Anything that doesn't work is a haggling point in your favor! The owner doesn't need to know that this is a commuter car for you and you alone, so you can always pull the "it'll cost me $300 to get this passenger heated seat fixed, so can we knock $300 off the price?" If you don't know what a button's function is, ask the owner for a look at the owner's manual.
By the way, this is also a great thing to do because if an owner doesn't have the car's manual, that is a pretty good indicator of being treated rough. As someone who takes very good care of their cars (to the point of it being anal and annoying) I don't know what I would do without a vehicle's owner's manual. If I didn't have one, I would immediately go to Ebay and buy one. Not having one in the car is a grave sign.
Service Records- A cheap vehicle with extensive service records is a diamond in the rough, and is always worthy of further examination. However, most cars this price won't have maintenance records. That means you are perfectly within your right to say something like "Since you don't have record of the timing belt changed, and I know it costs $600 for a mechanic to swap, can we get $600 off the price?" Make sure you do research ahead of time on what certain repairs cost for that make/model/year.
*As stated already, CarFax is no indicator of reliability. When buying a <$5000 car, I usually don't even bother with a CarFax report. It's a waste of time and 99% of the time tells you nothing you can't discern for yourself.
See How Long It's Been Sitting- A car that has been sitting for sale for 2 months will have an owner much more open to a lower offer. Craigslist ads will tell you at the bottom of the page how long the advertisement has been posted. If you see a car that has been reposted again and again, it may be worth sending the owner a low offer. You may just get a steal of a deal.