Picking a brand new domain does usually seem to be the best bet.
Net marketing guru John Reese has a tale of how he sold his first domain for $1,000. After the paperwork was signed, the domain broker let him in on a secret. He was actually buying the domain on behalf of a VC firm for $1 million. =)
The trick would be (if it still works) to always use a no-name broker or middleman to get the lowest price... but I'm no expert either.
Our default advice is that buying domains doesn't work. The owner either wants a ridiculous price, or doesn't want to sell, or doesn't answer your emails. There are also plenty of good names still untaken. We can often find one in a few minutes using instantdomainsearch.