They are called "completists"-collectors who simply have to have it all. And there are more of them out there than ever before.

Some are on the prowl for every one of the nearly 700 Beanie Babies ever produced. Others must own all of the more than 1,000 editions of "Alice's Adventures in Wonderland" or the 2,500 issues of TV Guide ever published. There are even completists who are dead set on obtaining an air-sickness bag from every airline in the world.

What has turned the simple hobby of collecting into a compulsive chase after completism? E-mail, e-commerce and, most of all, eBay. In recent years they've made it much easier to have it all. "The Internet has created more obsessively driven collectors, as opposed to people who just collect things," says Jerrold Pollak, a psychologist in Portsmouth, N.H.

"The world-wide community of collectors is so connected now. It's like, 'How did I ever get by without this?'" adds Duncan Jenkins, a 33-year-old chemist and "Star Wars" completist in Liberty, Mo. "Now as soon as anything comes out, it gets posted online, so everybody in the world knows that in Indonesia you can get this 'Star Wars' potato chip bag."

State of Perfection

What, exactly, is the appeal of owning everything "Star Wars," or, for that matter, everything Springsteen, Superman or Shakespeare? For starters, it's a link to the past. And as more and more baby boomers get nostalgic and take advantage of eBay's vast universe of recycled kitsch, it's no wonder that the site's "collectibles" category has become the most popular by far (1,420,971 items for sale at a time).

But as most completists admit, at times they can also be a little obsessive-compulsive. "Underneath a lot of this behavior is the desire to reach some magical state of perfection," says Dr. Pollak. "To feel, 'I've got it all.'"

Consider Mr. Jenkins. His goal: to get one of every single piece of "Star Wars" merchandise. He has spent the past 23 years accumulating 30,000 items-from Ewok Underoos to a life-size Han Solo made of carbonite. His house is fully Lucasized: he's eaten "Star Wars" bread and brushed his teeth with "Star Wars" toothpaste. Still he estimates that he's 70,000 pieces short of a complete collection.

To Mr. Jenkins, the Internet has been a mixed blessing. On a given day he might be faced with 32,877 "Star Wars" products on eBay. But such is the fate of a "supercompletist," one who looks to obtain everything on a given topic, not just, say, every poster or action figure. So while other "Star Wars" completists have decided to specialize in one type of merchandise, the force remains strong in Mr. Jenkins. Wanting it all, he says, is as natural to him as breathing. "I never put a limitation on what I was interested in collecting, and I won't," he says.

While Mr. Jenkins's endeavor might seem entirely futile, he's actually performing a valuable service to society, says Dwight Blocker Bowers, a historian at the National Museum of American History. Without completists, he says, "a lot of things would vanish completely, particularly in pop culture, and all we'd have would be photographs of them." In fact, the Smithsonian often borrows from completists when designing exhibits. And many completists end up writing guidebooks or finding creative ways to harness their expertise. Peggy Gallagher, of Burr Ridge, Ill., once ran up a $2,300 monthly phone bill to assemble three complete sets of Beanie Babies. Now she's doing a booming business separating the genuine plush toys from the fakes. Every day she "authenticates" some 25 to 50 of them for fellow collectors at $12 a pop.

Completism has always been a costly endeavor. To stay "complete," you have to buy things you wouldn't otherwise want or need. Plus, the truly rare pieces can kill you financially; all it takes is two collectors who absolutely must have something to drive the price through the roof. Mike Miller, a 53-year-old salesman in Tuscola, Ill., and his wife, Sherry, recently bid $2,600 on eBay for a Whiting & Davis mesh purse to add to their 1,000-strong collection; they thought it was worth $1,800, but they needed it for their collection. So did lots of other people. It went for $3,828.

The Verb

While the Internet has made completism more costly, it has also brought collectors together in new ways. Without the Internet, Philip Paul never would have come up with the idea of collecting ticket stubs from each of the 165 baseball games won by his favorite player, pitcher Sandy Koufax. For the past six years, he's sent 15 to 20 e-mails a day to people selling tickets or programs on eBay, and virtually all of them answer back to cheer him on. "It's remarkable; people really try to help you," says Mr. Paul, 51, a comptroller in West Chester, Pa. So far, Mr. Paul has found 107 out of the 165, for which he's paid an average of $25 apiece.

Mr. Paul's interest in these ragged old pieces of paper just goes to show what Pam Danziger, author of "Why People Buy Things They Don't Need," suggests: "We tend to think about people buying products, and the noun-the item-is what we focus on. In reality, people are buying the verb. What's driving a completist is the experience."

Indeed, part of the thrill is in never being complete. "Collectors don't really want to find that last item," says Ms. Danziger. "It's the eternal search for the holy grail. What would happen if you found the grail?"

It's a question that hangs heavy in the mind of Guy Ball, a 47-year-old technical writer from Tustin, Calif., who fears he might already possess nearly every pocket calculator manufactured in the 1970s. (He has more than 2,200.) He fell in love with the things 15 years ago at a thrift store. Before he knew it, he'd found 30, then 40, then a couple hundred at swap meets and garage sales. Through eBay he expanded his collection exponentially. It's a tough job-but Mr. Ball feels he just has to do it. If he ever knew he indeed had everything, he says, it would be "the worst day of my life."

Never fear, Guy: True completists don't ever let their collections die; they simply upgrade. Although he's far from the finish line, Mr. Paul, the ticket-stub collector, is already looking for stubs in better condition. He also hopes to replace the general-admission stubs in his collection with more colorful box-seat tickets.