The cheapest places to buy groceries are generally the least convenient," says Robert Krugoff, editor or Washington Consumers' Checkbook, a magazine that researches such information for its readers.

It's true that suburban shopping malls do not sport limited assortment stores, no frills operations or stores that sell dented cans. And in the metropolitan hjarea, none of these places is located inside the city limits.

Yet at a time there are so many households in which both the man and the woman work, fewer and fewer couples are willing to make food shopping an occasion for an excursion to the other side of town. Even for those who have the time and inclination, where's the gas goind to come from? Besides, is it worth it? Do you save enough money to justify the cost of the gas?

The price difference between Giant and Safeway, the two chains that control over 60 percent of the market, is 1 percent, according to Krughoff. Four chains, Giant and Safeway, plus A&P and Grand Union, control 80 percent of the market. The price difference among the four is 3 percent, or $2 on a $60 bag of groceries.

Krughoff, who will publish an exhaustive study of local supermarkets and independents in the August issue of Washington Consumers' Checkbook, reports that among the smaller independents and smaller chains, threre are "a couple whose prices are 6 to 8 percent lower than the two major chains."

"Warehouse stores," he said, "are 25 to 30 percent cheaper than the higher prices chains. Produced markets and stands are 30 to 40 percent below the chains and a co-op with 12 members can save 30 to 40 percent."

But Krughoff readily admitted that when you talk about two for more)-stop shopping "you are talking about quite a bit of inconvenience."

He thinks the only way to get people to shop at seemingly out-of-the-way places is to get them to think ahead, plan trips that include other errands or that "take advantage of their normal traffic patterns."

In addition the lower price stores are usually down the block or across the road from one of the major chains so all the shopping can be done without a lot of stop-and-go- driving. And trips to stores where non-perishables are cheaper can be once-a-month events.

Where are these bargain stores?

Scattered around the city. For most residents in the area, one money-saving store is likely to be convenient, if a shopper is willing to rethink shopping habits. Unfortunately, those who most need lower priced groceries are the ones for whom bargain stores are the least convenient.

Memco, a small chain of seven stores in nearby Maryland and Virginia. Five of its stores are within a mile of the higher-priced chains. According to surveys done by The Metro Consumer, Virginia Citizens Consumer Council and Washington Checkbook, Memco consistently has lower prices than the big chains. A Washington Post survey of three alternative markets, taken at the same time as the annual nationwide market-basket survey reported eleswhere in this section, bears out those results. In the nationwide survey the price given for each item is the lowest price found in the stores surveyed in the city. (In Washington, only Giant and Safeway were included.) Despite this, Memco's market-basket still was cheaper.

Comparing the prices of 32 out of the 35 market basket items (Memco did not have three of them in stock), it still cost almost $3 more to shop at Safeway Giant - $38 versus $35.20 at Memco.

Metro Consumer, a year-old newsletter geared to helping Washingtons get the most of the their money, conducted a 58-item pricing survey of supermarket chains in May, 1978. The Memco total at $86.64 was from $8 to $10 cheaper than the four other chains.

Last May, a reader wrote about Memco's pricing. Libby Yalom said she used to do her shopping at one of the two major chains but after she had spent some time comparison shopping she began to "do about 90 percent of my shopping at Memco." But she adds, "Memco's produce is very expensive, so I never buy fresh fruit or vegetables there. I don't buy meat there becaues I eat only chicken or fish."

Yalom compared 25 items and found that Memco was between 3 and 25 percent cheaper on all the items. The average was about 14 percent.

Krughoff believes that Memco's mix of software and household furnishing with the food is what allows the company to keep down its food prices. In addition, its range of items is more limited. Instead of six brands of peanut butter, for instance, Memco has three.

"Unfortunately," Krughoff says, "there isn't a Memco on every corner."

But if fresh, inexpensive produce is an important part of your weekly food budget, you could try Magruders, which as three stores in the metropolitan area. Each is near a major chain. After you have purchased the items for which Magruders had become famous: fruits and vegetables, some dairy products, especially eggs, and its meat specials, you should buy non-perishables at a regular supermarket for better values.

Comparing the total market basket of 32 items (Magruder's did not have the same kind of ham or the same size packages of flour and peanut butter) with the 32 item market bakset for Saeway-Giant, it would cost 34 cents more to shop in Magruder's. If, however, you bought only fruits and vegetables at Magruder's, your bill would be $3.84 instead of $5.04. Add the dairy and meat specials and you would have paid $7.05 instead of $8.64.

Co-op was the third of the alternative markets in which the pricing survey was done. The 35-item market basket at the store was $43.95, or $1.23 more than the cheapest prices for the Safeway-Giant total.

Another alternative market, not included in this pricing survey, is Bag 'n Box, a limited assortment store in Takoma Park. It is directly across the street from a shopping center which houses both a Pantry Pride and Giant. In an earlier survey by The Post, prices at Bag 'n Box were 10 to 15 percent below those at Giant. In a 27-item market basket (see story by Jane MeMouy, below) the cost was $36.74 at Giant, $30.73 at Pantry Pride and $28.03.

The conclusion is inescapable - to save money, shop around!