The price tag on the classic leather moccasin made the customer angry: "It's an outrage - $38! That's eight dollars more than I paid a year ago." So when the store didn't have the size she needed, she willingly drove off to another shop. But there, the price was $41.

The second retailer wasn't trying to gouge his customer-it was simply the new price for a slightly later shipment of the same shoe.

It's becoming almost as expensive to walk as to drive. According to the president of one of the nation's 10 largest show manufacturers, a family of five who busy some quality leather can expect a total shoe bill of at least $500 next year. That's about the same as the price of a year's gas for the family car-and $100 more than the tab for last year's shoes.

Although shoe prices have been rising continually, the recent stretch in the leather market means for greater increases for fall-and more still for next spring. Shoes that cost $30 to $35 last fall will be in the $40-plus range this fall; $40-to- $45 styles are to be $55 and more; and $100 shoes will cost at least $125.

"In my 15 years in business," says a major manufacturer of casual shoes for men and women, "I've never seen anything like it. And I see no end in sight."

In this situation, manufacturers and retailers are reluctant to quote prices: At the leather market in St. Louis in March, prices werer raised as often as four times a day. "I have a gut feeling," says Martin "Mickey" Schulman, president of the Joyce Show Company, "that there is no stopping the spiraling effect of leather prices."

The problem with shoe stock is livestock. Hide prices have more than doubled in a year. During the week of May 4, for example, hide prices were $1.10 a pound, up from 47 cents a year earlier, and up from $1.03 the week before.

Leather prices fluctuate with the state of the meat industry, and in the current cycle, cattle are in short supply.

"We're now down in the trough," says Fawn Evanson, executive vice president of the American Footwear Association. The price of meat is now high enough, she says, to give cattlemen the incentive to increase herds. But it takes three days for that increase to affect the leather market.

Worse yet, the world demand for leather is up while its availability is down. Argentina and Brazil have restricted hide exports, leaving the United States the major supplier on the world market. As a result, more than two thirds of U.S. hides were exported in the first quarter of 1979. With supply down and exports up, tanners fear the hide supply here may dip to half of what it was two years ago. (One tanner in New Hampshire recently advised his 200 employes that the plant would close this summer-mainly because of the high price of hides.)

The American Footwear Industries Association has put together a coalition of all leather users, tanners and retailers to see what can be done to pry loose more hides from the export market. Clothing manufacturers have recently joined in, hoping to stem the expected 25 percent or higher increase in leather garment prices.

At the same time, increased fashion interest in the tactile appeal of natural materials such as silk, cashmere and leather have boosted the demand for high-quality suede and leather garments.

So far, warm-weather purchasers of sandals and fabric shoes have not fully reflected the tight market. And "fortunately the fashion for boots is waning. Those prices would fly out of sigh," says a shoe boutique owner.

But retailers already worried about consumer reaction to fall shoe prices say it will be worse when next spring's styles go on the shelves in November.

Moreover, retailers have learned from some manufacturers that because of higher hide prices, shoes will cost more even if they were ordered six to eight months ago. "We know what is going on-so when the increases are reasonable, we have to accept them," says Frank Rich, a shoe retailer and member of the Commerce Department's footwear study team.

Harder to accept are the constant small increases with each shipment of basic shoes. "I've got new shoes to retail on one price, and the guy across the street has them at the old price," one retailer complains. "Eventually the others stores will have the new shoes and new prices, too. But till then, my customers will think I'm a thief."

The price pinch will be tightest on the customer who buys the middle to upper-middle-priced shoes. At the very top end, where men's and women's imported shoes will retail at more than $150, most customers are not likely to curb their spending. At the low end, where most shoes are made of petroleum-based synthetics, higher oil costs will not drive up prices as much as the cost of natural materials.

"Each new shoe must take a statement, must be imported before we'll bring it into the store from now on," says Rich.

Schulman of Joyce Shoes agrees. "With the new prices, we've got to give the customer a better reason for buying. She's not buying just to cover her feet."

One major retail chain buyer doesn't agree. "Last year we were looking to see what we could put into shoes. Now we're thinking about what we can take out," he said candidly.

Among the first things to go were leather soles and heels, since synthetic parts already are widely accepted in the middle-price market. "Some of the new synthetic soles, like Tunit from Germany are so good customers don't realize that they aren't leather," suggest one manufacturer. And knitted fabric linings, such as those used in boots to help them slip on easily, have been substituted in some shoes. "Cheap leather linings aren't nearly as good as some of the replacements," insists a manufacturer.

Except for summer, when women wear sandals, synthetics are not generally comfortable for shoe uppers. Like Corfam, the Dupont synthetic upper introduced in the 1960s, a closed synthetic shoe tends to be hot and lack flexibility.

With current leather prices, however, even Corfam is back under consideration. Dupont sold it to the Poles in 1963, and one manufacturer jokes, "maybe we will have to buy it all back."

One alternative to higher prices is to repair shoes already in the closet. Amedeo Mackenzie, manager of Woodies' shoe-repair business, says he is seeing a lot of pointed toes and old-fashioned heels-again-and is rebuilding them along more moderm lines. Cobblers, too, must pay more for leather. A complete sole-and-heel repair cost $20 two years ago. It is now $24. Ven half-soles for women's shoes, which use far less leather, are up about a dollar in the past year.

In the meantime, merchants are nervous. "I'm afraid," says Frank Rich, "that retailers are going to look like the 40 thieves, come fall." CAPTION: Illustration, by Jan Drews for The Washington Post