Right now, I think our entire economy is driven by sales of HD television sets.

I was in Kmart yesterday buying batteries and I overheard a conversation that started when a customer asked about flat-screen TVs. What’s the difference between the two kinds of TVs?, the customer shouted to the clerk at the register.

The clerk shouted back that one had a sharper picture.

Before the customer could ponder the difference, a grey-haired customer with a gravely voice waiting at the register added his opinion.

“You need a special cable to get the good picture!” the guy said. “It’s another $50. They’ll try to sell it to you as soon as you’re about to walk out with the TV box!”

The clerk added, yes, you do need the cable — but now they’ve started selling a short version of that cable for $25. Guilty!

Every place that sells consumer electronics should have a crotchety know-it-all walking the floor to warn his fellow customers customers about this sort of thing. (”Extended warranty? What are you, some kind of sap?!”)

Related: The DTV transition is one year away: Feb. 17, 2009. This will cause mayhem and unrest like nothing seen since the 1960s! See DTV2009.gov.