all the above, also i usually check the car enthusiasts forums, you usually find cars on those have been very well cared for.
Buying from enthusiast forums can lead to hugely exaggerated pricing.. Buyer beware.
I still find the best place to buy cars is from the Auto Trader, bought a couple recently for members of the family, you can haggle the price down, look at the car before your buying and not go through all the nonsense of Ebay.
With the economy the way it is, its a buyers market, if someone is asking £2000 for the car you want, dont be afraid to put a silly offer in first, like £1500-1600, go away if you have to, give them your number, you never know once someone stews on it what they will do for the cash.
If your not in a rush you will get a real bargain.