I'd buy it from Craigslist or Cycle-specific message board in your area if you're concerned about price.
If it's within the first year of being 'used' it will not have been broken in too much.
That said, I bought my Brooks Team Pro from http://www.benscycle.net/.
Also, consider fit bone width before purchasing a brooks saddle; go into a bike store and ask if they have a fit bone measuring device (usually by Specialized). I've found that some Brooks saddles can...