I'll add my 2 cents worth.
Financially you are right about leasing. Leasing is renting. Don't ever lease from savings, lease from your net pay. I personally don't believe in leasing unless there is some financial benefit from business.
As for whether ot buy new or used, financially speaking the best situation is a current model (2006) from the dealer that has been driven (a few thousand miles or so). You get the warranties, basically the same useful life as if new, and you'll pay 10% less. Next year you will have the same exact car as the guy who paid full price.
Only problem is....good luck finding a demo Prius.