An idea along these lines was touched on (for a different purpose) by marginalrevolution.com a few months ago. It is used as an ingenious method for airlines to discriminate bwteen those flying for business (who tend to pay for more tickets) and those flying for pleasure (who are more price sensitive).
http://marginalrevolution.com/marginalre...o-fly.html
http://marginalrevolution.com/marginalre...o-fly.html