The problem is particularly prevalent among first-time buyers and young people trying to purchase budget homes at Melbourne auctions.

Consumer Affairs Victoria has been cracking down on agent underquoting following the introduction of new laws aimed at stamping out the practice.

A key plank of the reforms is that agents must provide prospective buyers with the details of three recent comparable sales of similar properties in a statement of information.

But market watchers say there's still a lack of uniformity in the way houses and units are being quoted, and agents are featuring "not so relevant comparables" in their statements.

These comparables suggest that the property up for auction or private sale could go for a much lower price than it actually does.

Late last month, observers reported gasps of surprise from some of the 100 onlookers gathered for the auction of a one-bedroom apartment in St Kilda East.

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Selling agent Gary Peer provided details of three recent sales in the suburb, for flats that sold for between $370,000 and $405,000, but the top-floor unit at 15/26 Hughenden Road rocketed ahead of the estimate.

Five bidders, all property investors, thought the 1970s-style, balcony apartment had merit. The quote range provided under the new anti-underquoting laws was $370,000 to $400,000, but the opening bid for the unit was $400,000 and it sold under the hammer for $548,000.

Was this an open-and-shut case of underquoting?

No way, says Gary Peer director Phillip Kingston.

"No one was more surprised than us by the end sale price," he said.

"The sale price was unexpected and unprecedented. Our reserve provided on the day was within the range we quoted of $370,000 to $400,000. There was no apartment comparable to this that sold for the price it achieved."

Property experts say numerous properties are being conservatively - but legally - quoted.

Buyers' advocate Caroline Swinden, from PropertyDuo, said another unit in the same Hughenden Road block sold seven years ago for a higher amount than the quote range provided for the unit auctioned last weekend.

"Some agents are doing the right thing with their quoting," Ms Swinden said. "Others look like they are manipulating the system by using not so relevant comparables in their statement of information. This will make it really difficult for first-home buyers."

Sources say major agency groups have sought legal advice on how they can legally price quote properties but still entice buyers who might be looking to buy at a lower price point.

Mr Kingston said the Melbourne market was experiencing plenty of situations in which properties achieved unexpected premiums.

He said a nearby one-bedroom apartment with a courtyard (which the Hughenden Road apartment didn't have) sold an hour later on July 29 for almost $100,000 less than the price Gary Peer's sale achieved. "A two- bedroom apartment sold the next day around the corner for a lower price than what we achieved."

Consumer Affairs has commenced action against 12 agencies for alleged underquoting, and investigations and court cases are continuing. Since May, agents found guilty of underquoting have faced fines of $31,000 as well as the loss of commissions.

It's important in the current climate that buyers do their own research.

Certified valuer and buyers' advocate John Sommers, from McRae Property, said he often didn't look at the agent's comparable sales in the statement of information when assessing or valuing a property.

"I do my own research because it is quite common for properties to sell above the quoted range - there's plenty of evidence of that," he said.

Another buyer advocacy operation, Wakelin Property Advisory, argues that buyers need to consider a value that takes account of sentiment in the market and not just a technical value.

Wakelin director Paul Nugent believes buyers should always calculate technical value - a value based on recent sales and metrics such as historic growth and yields - but they also need to factor in strong upward sentiment, particularly for houses, and adjust their expectations upwards.

Mr Sommers said underquoting was still going on but it was less overt than previously.

He said a townhouse currently on the market had a quote of $800,000 to $880,000 but would easily command $920,000 at auction.

"The agent is saying the top end of the range is $880,000. I think it is underquoting but it is not dramatically underquoting; it could be a consequence of the agent just being a bad judge or it could be a case of the agency wanting the quote to be a fairly conservative number."