In reply to Newbuild100:
You'll find most aftermarket warranties exclude 'wear and tear'. Pretty much any serious fault on a car could be blamed on wear and tear. There might be a few decent aftermarket warranties out there, but there are far more that aren't worth the paper they're printed on.
A 3 year old well maintained car should have had all the obvious defects sorted, and pretty much any of the big manufacturers models should do well in excess of 100,000 miles if looked after. You might be unlucky, but a bit of reading up on the issues with the model you're buying should minimise the chances of that happening.