An auctioneer barks out numbers in rapid-fire rhythm. In a standing-room-only crowd, proxy bidders hunch over their mobile phones and cover their ears. Auction-house assistants fan out and move close to bidders who seem most intent on winning.

What's at stake isn't contemporary sculpture or an Old Master painting on the block at a Manhattan auction house. It's an old tractor, a 1960s John Deere, at a recent auction in New Paris, Ind. After it sells — for $57,000 — and it's time to drive the tractor away, there are so many spectators trying to get a closer look that the sleek machine can only inch its way gingerly off the block.

Old tractors like this one are exerting a new kind of pull. As collecting interests a broader, wealthier audience, prices for many models, especially those more than 40 years old, have surged. Some of the oldest tractors — early 20th-century machines often powered by steam — can now fetch $100,000 or more, up from about $10,000 a decade ago. Rarer models can sell for much more.

Beauty in the Beasts of Burden The market for vintage tractors is heating up. Here's a look at some classic vehicles.
	Co-op tractors are rare, but generally not as sought after by collectors as vintage John Deere models. This neat example sold for $5,700 at the Dennis Polk Spring Fling auction in New Paris, Ind., on March 8, 2008.
	Looking more like a sports car than farm equipment, this restored John Deere 3020 Orchard has smooth bodywork to keep wheels, gears and protruding parts from damaging delicate fruit trees.
	A ringman stirs the crowd and keeps track of a flurry of bids for the John Deere Orchard. It eventually fetched $57,000.
	A 1930s Farmall F-Series with steel wheels has the original look and decades of patina some collectors seek.
	A steel-wheeled John Deere B waits in line to cross the block. It sold for $2,900 — considered modest in today's brisk tractor market.
	Another antique John Deere crosses the block in Indiana.
	Companies other than John Deere built orchard tractors, like this sleek restored model by McCormick-Deering.
	Carl Blasig, a flower farmer in Chesterfield, N.J., shows a recently purchased Allis-Chalmers D21 that he plans to restore with his son, Zach (in the driver's seat). He says he paid $12,000 for it.
	Duane Ver Ploeg just finished restoring this tractor for a customer at his restoration shop in Sully, Iowa. It's a John Deere 2520 high-crop, a rare 1969 model of which just 19 were built. These are like the muscle cars of the tractor market in that Baby Boomers increasingly seem to relate to even if they didn't grow up on a farm. This restoration took 400 hours and cost $40,000. But the tractor is so sought-after that it would probably fetch more than $150,000 at auction.

While farmers have dominated the antique-tractor market in the past, they are now bidding against a new, well-heeled breed of collector. The influx mirrors the trend of city slickers buying up farmland for vacation homes in rural parts of the country.

Dave Anton, a 47-year-old financial planner, grew up around Pittsburgh with no agricultural background. He had a collection of rare cars before a friend introduced him to antique tractors about seven years ago. "I was pretty well hooked after that," he says. Mr. Anton and his family had recently moved to a large property in rural Beaver County, Pa., where he had plenty of room to drive and display his tractors. He treats them gently. "I don't run them in the dirt anymore."

Other types of buyers, too, are fueling the run-up in prices. With grain prices surging to historic levels, many farmers have more money in their pockets. And even in the heart of the Midwest, European collectors are jumping in to take advantage of the weak dollar.

A seasoned collector might be willing to pay a few thousand dollars for a fairly common John Deere Model B, says Mark Stock, co-owner of Stock Auction Co. in St. Edward, Neb. "But if someone with money who is new to the hobby really wants it, he'll write a check for whatever it takes."

The result is a rise in prices that longtime enthusiasts say is making it harder for them to continue collecting. Some European collectors "are blowing us out of the water," says Duane Ver Ploeg, a restorer in Sully, Iowa, who just returned from a big auction in Nebraska where an unusual number of overseas collectors were bidding via the Internet.

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The following is a selection of original tractor literature.

Today's collectors pay a premium for rare models, like high-crop machines with raised axles that allow crop cultivation after the plants have grown a few feet high. Other sought-after types include "orchard" tractors like the John Deere that sold for $57,000. They have striking-looking fenders that protect delicate orchard trees and winery vines from the tractor's wheels. "We had a John Deere 3020 Orchard model sell for $160,000 recently," says Brian Zehring, a spokesman for auction company Dennis Polk Equipment in New Paris, Ind., the company that auctioned the rare John Deeres last month. Extremely rare machines can fetch $300,000 to $400,000.

The new interest is also boosting the tractor-restoration business — as well as the standards for restoration. Once, the job required little more than a wire brush to scrape off rust and a few cans of spray paint that approximated the machine's original color. Today, collectors want their tractors to look new, with pristine sheet metal and all the proper parts, including the original engine. This can be hard to accomplish, because farmers often changed their tractors' parts and replaced worn-out engines over decades of ownership.

"I want tractors that are as factory-original as possible," says Mr. Anton, noting that the quality of collectible machines has risen in the past few years.

Restorations can easily cost tens of thousands of dollars for tractors that are in rough shape or are missing obscure parts, many of which have to be reproduced by hand.

Specialists like Mr. Ver Ploeg, who recently finished a 400-hour restoration of a rare John Deere tractor, typically charge $50 or more per hour — the same rate as some classic-car restorers. Tractor restorers face the same pitfalls as car restorers, too. Inappropriate replacement parts or paint that isn't the right shade can significantly alter a machine's value. At the recent Indiana auction, another rare John Deere model, made even more unusual because it was powered by liquid propane instead of diesel, drew a lot of interest. But it failed to sell, in part, experts say, because it lacked its original serial-number tag.

Carl Blasig, a longtime flower grower who collects Allis-Chalmers tractors, points to a pair of big four-wheel-drive models parked at his Chesterfield, N.J., farm. One of them is painted a darker shade of the manufacturer's signature orange. "Over the years, they used three different shades of orange, but the darker color is wrong for this model," says Mr. Blasig, who has about 40 tractors. "I'll have to repaint it myself eventually."

While many antique tractors seem quaint by modern standards — small, underpowered and loud — they were high tech for farmers of a century ago, who had previously used plows drawn by draft animals. Farmers could also attach accessories like balers and mowers — now in demand as well among collectors — to cut the time needed for chores.

Even Porsche built farm tractors during the 1950s, and the vintage machines are as sought after by collectors today as some of the company's antique sports cars. Whether from Porsche, John Deere or McCormick or Massey-Ferguson, vintage tractors mostly lead easier lives now than they did when new. Buyers enter them in shows, drive them in parades and compete in tractor-pull contests. Newer buyers tend to keep their pristine purchases in sheds, or drive them around their yards.

Some traditionalists, however, continue to work the soil, even with 50-year-old machines. Mr. Blasig of New Jersey says he likes to hear the stalwart chug of his tractors' engines.

"I make a point of using all of them," he says.