First of all, I would be concerned the least about a lifetime warranty on a frame. I'd worry more about it being hit by a meteorite than failing due to a warranted defect.

Then, as Classtime suggested Craigslist. The owner of my LBS has breakfast with owners of stores from nearby towns on a regular basis to keep abreast of regional goings on. He says they all agree that a high percentage of the new bikes they sell end up on CL a few years later with less than a hundred miles on them.....for half, or less, of the original price.