Buying a piano for a beginner?

I am learning to play the piano and I have a few questions about buying one. 1. Old or New? 2. What makes should I look for / avoid ? 3. How much should I spend? 4. Any other things I should look out for?
Update: England, Southampton.
Update 2: Good to hear about Rocking Rooster, I was going to buy my guitar from them, but was concerned because they were so much cheaper than everyone else. But now you have said how good they are I can just save myself a fortune!
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