batteries, which often are not on sale at the checkout counter. in fact, you may not even need to go into a store at all. >> that's really the number one strategy, is to do some of that shopping online before you even want to go to a store because so many of these stores that have black friday doorbusters will actually have those doorbusters available at their website. >> reporter: of course there are things you'll want to take advantage of, like videogames, and dvd and blu-ray movies, which will be deeply discounted through sunday. and if you are hitting the stores this weekend, bring along your smartphone. apps like red laser by ebay allow you to snap a picture of the upc code on the item and then it tells you which other stores sell the item for less. so if you're wondering what might possess people to camp outside of a store, well, feast your eyes on this sharp 42-inch tv. it'll be selling for $200 on black friday. it would normally go for two or three times that. each best buy will have at least ten of them. they're expecting competition to be fierce. linsey davis, abc news, jersey city. >> that's a really good deal.