By Richard Chang

NEW YORK (Reuters) - Buying or selling online? The question that lingers on everyone's mind is: "How much is an item really worth, and how do you get the best price?"

The answer, which comes at the end of an auction, may not be definitive. After all, the value of similar items can vary widely depending on their condition and history, and where they're sold.

"You can get a ballpark figure" from looking at price guides, said Terry Kovel, one of the foremost experts on collectibles. But even with standard items like cars, prices vary depending on the condition and mileage, she said.

To provide the assurance that an item is worth the asking price, appraisers are offering their services online once again, after Eppraisals failed in this venture a year ago despite $15.5 million in capital funding. This time, appraisal operations are cut down to the bone, though customers still pay up to $19.95 for each opinion.

"Ninety-eight percent of Americans don't know what they own: the significance and value of appreciable property," said David Maloney, director of appraisal services for CollectingChannel.com, which made its debut on eBay (http://www.ebay.com)EBAY.O last week. "This mass market of owners of property just want to get a feel for what they have."

The Collecting Channel's (http;//www.collectingchannel.com) $19.95 fee for its "Ask the Appraiser" service is a mere fraction of the $75 to $250 per hour rate that professional appraisers charge for looking at an item in person.

What's It Worth To You (http://www.whatsitworthtoyou.com), which was launched a year ago, charges even less, at $9.99.

"This is not a new type of appraisal at all," said Maloney, the publisher of Maloney's Antiques and Collectibles Resource Directory. For items that have been stolen or have perished in floods, fires or tornadoes, appraisers regularly assign values based on photos, verbal and written descriptions and catalogs.

"We're doing the same thing online," he said. "The only difference is that it used to come to us through snail mail."

Collecting Channel has a "modest goal" of providing 1,500 appraisals a week, compared with up to 7,000 industry-wide up to a year ago, said Gregory Rotman, president and chief executive of Sales OnLine Direct, parent of the Web service.

What's It Worth To You had 25 to 30 appraisals a day about four months ago, when the volume started to grow 10 percent a month, Erik Kafrissen, president of the company, said.

On these sites, users are guided step by step to provide details about the item they want to price. A report is furnished, with those details and an appraiser's opinions, for a seller to include with a listing on eBay, for instance.

"We're taking the information a customer gives us," Kafrissen said. "The appraiser may say you need a hands-on appraisal after an online review."

Kovel said collectors can get just as good an indication of an item's value by visiting http://www.kovels.com for free, or consulting other price guides -- which is what appraisers do anyway.

"To say I know this is a Tiffany lamp is not an accurate description. You have to have a picture that's clear, a mark, a family provenance that can be verified, not a story grandma told you in her dotage," Kovel said.

"If it's something that's one of a kind, an oil painting, you need an expert. Chips, cracks and breaks matter a lot, or even a flake of paint in the middle of the girl's face." These details may be tough to pick out in a photograph, online or offline.

MastroNet (http://www.mastronet.com), an online auctioneer for high-end collectibles, has a feature on its online catalog that allows viewers to zoom in on a picture. Prospective bidders who want more assurance may visit the company in Oak Brook, Illinois, to check out the items in person, though only a handful of buyers ever do, said company President Doug Allen.

To add another layer of protection, MastroNet guarantees the authenticity of its items, helping sellers to get a better price.

"If you're selling something of high value, you need someone to add another level of assurance, do the legwork properly and prove the provenance," Allen said.

After MastroNet did the legwork, the Ford Museum paid $500,000 for the bus in which Rosa Parks, a black worker, refused to give up her seat to a white passenger in 1955, thereby sparking the Civil Rights Movement.

Before that, the vehicle -- which the seller's family bought from the bus company and used it as a toolshed -- failed to attract bids that met the reserve of $75,000 on eBay.

MastroNet charges both buyer and seller a 15 percent premium on the auction price, and positions itself in between eBay and brick-and-mortar auction houses Christie's and Sotheby's BID.N .

"When you're selling an antique the amount you get is directly proportional to the amount of effort you put into it," Kovel said. "If you have a big house sale, call in a dealer. They're going to get bargains, but you won't get the headache. If you have Chinese export porcelain, you should go to an expert."

In any case, an appraisal does not guarantee that an item will sell for the assigned value. Prices can vary greatly in different locations, or even between eBay, MastroNet and Christie's.

"It's a calculated guess," Kovel said.

(This column appears every other week. E-mail any comments to richard.chang(at)reuters.com).