Ron Lollar's standard lunch, culled from the vending machines at the Agricenter International, is a honey bun, barbecued potato chips and a Coke, enough sugar and salt to send a nutritionist into shock.

"Most time, I don't even do that," Lollar said with a guffaw, "but if I've got a choice of a nice big lunch, that's what I eat."Richard White, another Agricenter vice president, can't stay away from the vending machines either; his favorite snacks are Milky Way and Snicker's candy bars and cheese crackers.

Ah, those glass-fronted Sirens; sitting at your desk, you can hear their warm humming, their sweet promises of momentary release from the stresses of the business day. "Bring us quarters," they sing, "dollar bills, too."

Americans bought more than $21 billion worth of products from vending machines in 1987, the latest year figures are available. That compares with $10.7 billion in 1977.

"Vending machines are so important that we now take them for granted and don't even think about them anymore; good, bad or indifferent, they're just there," said Walter Reed, who handles public relations for the National Automatic Merchandising Association in Chicago.

Interestingly, the number of machines over the past 10 years has remained fairly steady at somewhere between 6 million and 7 million; what has increased dramatically is the number of items, going from 6.7 billion in 1977 to 8 billion items in 1987.

The reason? Today's electronic "merchandiser" sells 35 to 45 products compared with the limited number of items dispensed by yesterday's mechanical nine-column candy machine.

"Thirty years ago we were selling mostly cigarettes, candy bars, cups of cola and cups of coffee," said Tom Dayton of Serv-O-Matic Inc. "Now we're seeing a wide variety of perishable goods, sandwiches, snack items, including some 20 kinds of chips and corn snacks and another 20 or 30 kinds of cookies, together with a wide variety of candy bars."

Vending machine sales boomed in the 1960s and early '70s; growth since then has been fairly steady.

"By 1975, in America, there were not too many places that didn't already have them," Reed said. "Therefore, the placement of machines since that time has plateaued. We now get additional machines in new construction, but in the rest of America we've pretty much saturated the market."

Are vending machines truly everywhere?

"Nowadays nothing is really sacred; we have one in the cemetery," said Robert Traphofner of Canteen Food and Vending Service, referring to the vending service for employees at Forest Hill Cemeteries in Memphis.

Some parts of the industry, however, are enjoying faster growth by serving the unmet needs of a rapidly changing work force. Office coffee services, for example, are willing to take on offices with four or five workers, groups too small to justify a full-fledged vending service.

While the industry grew at 7.8 percent, fruit juice sales grew at an astounding 58.2 percent in 1987 over 1986, according to Automatic Merchandizers magazine.