The price of T-bone steak is down.

So are the prices of gasoline, computer equipment, air travel, Glad Bags, lettuce and certain French wines. Houses are selling below their appraised value in some cases. Automakers are giving discounts and rebates. And everything from designer jeans to washing machines have been put on sale by merchants anxious to reduce their inventories.

Even though the Consumer Price Index released this week showed prices in the Washington area rising by 8.1 percent over last year, the news is not all bad for consumers. Several things, in fact, have actually gotten cheaper since last February.

The reasons are as varied as the goods, but in general the reductions represent the response by manufacturers and retailers to a depressed economy in which consumers need every possible encouragement to part with their money. "As long as uncertainty about the future economic course remains high, this sort of trend is likely to continue," said Phylicia Fauntleroy, senior economist with the Washington firm of Brimmer & Co.

Two additional factors, besides the attempt to stimulate buying, have been bumper food crops and the continued world oil glut.

Gasoline price wars, for example, have broken out in the Washington area for the first time in several years. One of the fiercest battles is now under way, for example, along the short strip of U.S. Rte. 1 that extends from the Beltway to the University of Maryland in College Park.

The price of gasoline at the eight stations crowded along this 1 1/2-mile road has been dropping steadily since mid-December when the College Park Texaco reopened under new ownership and began trying to increase sales by decreasing prices. Regular leaded gasoline for cash customers at the Texaco station has fallen six cents, from $1.179 a gallon on Dec. 9 to $1.119 a gallon this week. Credit card customers pay 15 cents a gallon more than that.

"The other dealers aren't too happy," said Texaco station manager Brian Magee. But Magee, a chunky man with oil-stained hands and a blond mustache, said the price cutting strategy has worked. "We have doubled our volume in two months," he said.

Other stations in the Washington area have also been lowering prices, due to lower wholesale costs and oil company rebate programs aimed at increasing sales of gasoline. Competitive pressure, of course, is a major factor in reducing gas prices, just as it is in the fare-cutting battle now under way among airlines flying West Coast routes.

Another oil product that's gotten cheaper in recent days is heating oil. The most significant reductions so far have occurred in the wholesale market where there have been cuts of as much as 25 percent, but the major decrease in retail heating oil prices isn't expected to occur until companies have replaced their present inventories, which were bought before the wholesale price reductions, with less expensive heating oil, according to marketing specialist Herb Triplett.

Prices already have decreased on some food items, however.

T-bone steak now costs an average of $3.96 a pound in the Washington area, down 20 cents a pound from January and down 53 cents a pound from the 1981 price, according to surveys by the National Cattlemen's Association. The price changes reflect the adequate supply of meat that is available and retailing price decisions to feature T-bone at particularly attractive prices, officials said.

Lettuce, which soared to $1.19 a head at some area supermarkets after the Florida freeze, is available now for 59 to 69 cents a head here because of an improvement in the supply. The same is true for some vintages of imported wine.

A bottle of Pouilly Fusse' from the white burgundy district of France is selling for $9.99 now at the Cheese and Bottle, an Arlington specialty store. Six months ago that label was $12.99 and a year ago it was $14.99, according to store owner Jay Fast.

"They had acres and acres of grapes (for Pouilly Fusse') and they glutted the market," Fast said.

In the case of the electronics industry, rapid technological advances have made lowered production costs and led to frequent retail price cuts. Several years ago, it was calculators; now it's pocket computers.

For other industries, however, lowering prices usually means an attempt to boost declining sales. The manufacturers of Glad Bags, for example, began advertising on television that they were reducing the price of sandwich bags by about six cents a box and trash bags by about 14 cents.

For two of the nation's most depressed industries--automobiles and real estate--that kind of price slashing to stimulate sales has become a fact of life.

A four-bedroom colonial brick in Fairfax County, in what is becoming an all-too-familiar example, was appraised last summer at $129,500. The owner wanted $132,500. But after sitting on the market for 120 days, from June until September, the house was reduced in price to $119,950. Nothing happened. Finally, on Feb. 15, the house sold for $115,000--nearly $15,000 less than the appraised value.