Despite the tough economic climate, flat-screen television sets remain among the most popular items for holiday shoppers — at prices that continue to drop.

Ross Rubin, director of industry analysis at the NPD Group, said there have been strong sales this year of HDTVs that cost less than $500, with both Walmart and Target offering 32-inch LCD sets on Black Friday for $250.

“Thirty-two inch is popular now because you have a lot of early adopters who purchased their big-screen flat-panel TVs a couple of years ago and now they are coming back for a second or third TVs for bedroom and so forth,” Rubin said.

He also said some consumers who bought a converter box for their analog sets during last summer’s digital TV transition may also now be buying their first HDTV.

The average price of a 40- to 42-inch flat-panel TV was $838 during the first nine months of the year, down $312 from the same period last year, according to the NPD Group. For 50- to 52-inch sets, the average price was $1,409, down $532 from last year.

Through the end of October, the most popular LCD sizes are 32 and 19 inches, while the most popular plasma sizes are 50 and 42 inches, according to the NPD Group.

Rubin said that we are “close to the floor” of the HDTV market as a 32-inch set costs about the same as comparable tube TV did 10 years ago.

Q: What about all of these new “LED” TVs?

A: This year, there’s a new type of TV being sold, which is sometimes referred to as an “LED” TV. However, it’s more accurate to call it a “LED LCD” TV, since LED refers to the type of lights in the TV, not the screen itself. Vizio, Samsung, Sharp, Insignia and Toshiba are all selling LED LCD TVs.

LED LCDs differ from conventional LCDs because instead of using florescent tubes (which have trouble creating dark blacks) to light the screen, they used LEDs, which use less power and can do a better job creating deep blacks. There are actually two kinds of LED LCD TVs: “edge-lit,” which feature LEDs placed around the edge of the display, or “rear lit” (also called “backlit”), which features LEDs across the back of the display. Rear-lit sets can create deeper blacks, but they are the more expensive type.

Although using LED lights helps LCD sets move closer to plasma sets in picture quality, they are more expensive than similarly sized plasma or LCD sets. They are thinner and consume the least amount of energy, but both plasma and LCD sets now consume a lot less power than they used to, and there are Energy Star-certified sets available.