Austerity doesn’t come naturally to Americans. Even when cutting back on their expenditures, many folks can’t bring themselves to shun some big-ticket items they’ve coveted. Fancy TV sets fall into that category, judging by The NPD Group’s retail-tracking data. In September, unit sales of flat-panel TV sets were 20 percent higher than they had been a year earlier. For flat-panel sets of 40 inches or more, unit sales were up 30 percent. If consumers are going to hunker down at home during the economic hard times, they’ll at least do their hunkering in front of a nice TV set.