The price of everything just keeps going up, right? Wrong!

Question: What do gold, diamonds, TV sets, airplane tickets, and gasoline have in common? Answer: Their prices have fallen.

While President Reagan, Congress, and John Q. Public focus on inflation, lots of things are actually going down in price -- often way, way down.

The latest consumer price index figures from Washington offer examples: Gasoline, for instance, dipped an average 1 penny a gallon for all grades in August. And there were steep reductions in some food items such as portershouse steak, which showed the largest drop -- 14.8 cents less per pound on a national average.

But the deflation of some products has been around much longer than just the latest month, according to a report by Ray DeVoe, a market strategist with the New York consulting firm of Legg Mason Wood Walker.

For example, he says, a shopping list including a television, calculator, digital watch, airplane ticket, and even the ball point pen to sign the tab with , would likely cost less today than a year, or possibly even 10 years, ago.

While relief in the upward price spiral is less than obvious to the average consumer, deflation is present in a sampling of 30 items Mr. DeVoe found, with an average price decline of 25.4 percent over the past year.

"There are a lot of things coming down, including the inflation hedges of a year and a half ago . . . deflation is quite pervasive," he says. "When people think of inflation most of the time it's considered literally a gut issue . . . because food increases regularly. But there are other areas that prices have been declining."

Consumers, paying $276.50 today for goods it took only $100 to buy in 1967, have been conditioned to perpetual inflation. But, says DeVoe, deflation isn't surprising: "The history of this country is not inflation. If anything, it's been wild swings involving deflation. Between the Revolution ad the Civil War, prices were unchanged. From the Civil War to 1939, they were unchanged."

Other economists agree that many prices, while maybe nor perceived as cheap, are cheaper than they are were. And the trends behind some of the decreases -- like deregulation and increased technological efficiency -- could intensify, they say.

"Computers are a good example for prices actually falling," offers Vincent Malanga, senior economist with A. Gary Shilling & Co. The consulting firm forecasts that inflation wil slow considerably in 1982, with consumer prices increasing at an 8 percent annual rate compared with this year's projected 10 percent increase and 1980's 13.5 percent increase.

He also cites decreases in diamonds and gold. The price of gold has been "cut in half from a high of $800 an ounce in 1980." (DeVoe's study concurs, showing the price of a 1 karat, D-quality diamond a year ago was $72,000,and at the release of the study early this year it was $50,000. Now, he says the price is nearer $43,000.)

Steve Resnick, an investment strategist with Merrill Lynch, agrees with Mr. Malanga, adding that cars are another example of lower prices: "On rebate sales, some cars are cheaper than they would have been last year. Take this year's models, some debates cut the price up to $1,000."

DeVoe's "Incredible Shrinking Price Tag" report, in which he compared year-ago prices on selected items with prices on the same items early this year, indicates that technological advancements, deregulation, and competition are the reasons behind current deflation.

"I think technology is a downward price street," explains DeVoe. The magnitude of technological improvements is reflected in the fact that even rising labor costs haven't offset savings, he explains. Such advances in technological efficiency have sparked a competitive boom that offers the consumer real bargains in the electronics field, he says.

"Hand-held calculators were originally introduced at around $200, now they're down to $15 or $20 . . . a 12-inch Zenith black and white TV as $94 and now it's a Seiko digital watch was $175 and was down to $135 and probably is less now . . . one radio-cassette player came down from $279 to $219 . . .," says DeVoe.

A Monitor survey of some electronics prices found that Texas Instruments (TI) Inc. introduced its first hand-held calculators in 1972 for $149. Its cheapest today retails at $9.95.

"We learned how to make them faster and better," say Cheri Fitzpatrick,a TI representative.For example, today's six-function model 1750-3 calculator, at $15 .95, is an improved and cheaper version of its predecessor, the model 1750 which , introduced in 1977, held steady at $24.95 until June.

A Boston jeweler says that Timex digital watches have dipped to the $25 range -- half what it was last year.

And Bic Pen Corporation offers its standard ball point pen in quantities of nine for 19 cents apiece; individual pens sell for 29 cents, the same price they were when introduced in 1959.

Flicking the popolar Bic Lighter costs nearly 50 percent less than the product's introductory $1.49 price in 1973.

Plastic used in these products are oil derivatives and the ratio of high oil prices rises comapared to stable or decreased prices illustrates the increase in manufacturing efficiency, a Bic spokesman says.

The deregulation movement, as well as increased competition in certain areas, has helped deflate prices like those for air fares, where deregulation caused an initial flurry of rate reductions, says DeVoe. But competition has battered prices further in recent weeks.

Eastern Airlines, for example, reduced the price of a ticket on its Boston to New York shuttle from $56 a year ago to $49 last spring. This month it extended the $29 weekend fare to midday flights on weekdays. Similarly, the airline this month reduced its one-way fare from New York to Florida from $149 to $79 -- the lowest that fare has been in 10 years ($78 in 1971).

certain telephone costs also have gone down as the industry has been opened to more competition. DeVoe's survey found the price of a non-Bell system plug-in portable telephone to have dropped during the year of the survey from $ 69.95 to $39.95. The Bell System's cheapest phone is $89.

Also, phone rates have seen some dips due to deregulation and better technology, says an AT&T spokesman. In June, the international direct dial rates were decreased 35 percent on the initial three-minute period. Now a call to the United Kingdom costs $3 for three minutes during the day and $2.40 for three minutes on weekends and evenings. Those rates compare to pre-June rates of roughly $4.60 day and $4 weekends and evenings.

Satellite and undersea cable technologies have made international calls cheaper and increased the volume of calls, which enables prices to be furthere reduced the spokesman explains.

Increased competition has been the major factor behind a drop in gasoline prices, says Trilby Lundberg, associate publisher of the Lundberg Letter, a California-based oil industry publication.

Although gasoline prices are higher than 1980 levels, there has been a steady decline since the March 1981 peak of $1.3782 a gallon -- a combined weighted average of the four gasoline grades at 15,000 self-service and full-service stations surveyed by the firm. The survey average in August was $1.3428. But, says Ms. Lundberg, the monthly decrease appeared to be slowing between July and August.

"The reason for the drop has been oversupply and shrinking demand," explains Ms. Lundberg.