MOST home sellers know that the broker's commission is often negotiable. What many do not know is just how negotiable that commission can be.

In fact, while 5 and even 4 percent commissions are becoming more common, instead of the old standard of 6 percent, it is possible to find brokers willing to list a property for a 2 percent commission.

Whether the size of the commission should be the bottom line in choosing a broker, however, is a subject that evokes strong feelings among real estate specialists.

"It's very tempting to try to save money on the commission," said Dexter Guerrieri, president of Vandenberg Real Estate in Manhattan. "But in most cases, the money you save is probably going to be lost somewhere else."

Mr. Guerrieri said that with sale prices in many areas at record highs, shaving even a single percentage point off the real estate commission can save the seller thousands of dollars. A typical sale arranged by Vandenberg, he said, can range from $1 million to $3 million or more. A commission of 6 percent on a $1 million sale is $60,000. At 5 percent, the commission is $50,000, a savings of $10,000.

But that savings could easily disappear, he said, if the house or apartment does not sell for the best price because it is not being actively marketed to as many potential buyers as possible by the largest number of brokers.

"There's a trickle-down effect when you start discounting the commission," Mr. Guerrieri said. "And in many cases, a reduced commission is reflected in a reduced sale price."

He said that in most cases, when a property is sold by a broker other than the listing broker, the two divide the commission.

In areas where there is a Multiple Listing Service, participating members have a contractual obligation to split commissions with other members. In areas where there is no official M. L. S. — including Manhattan — brokers typically have informal co-broker arrangements to share commissions.

However, Mr. Guerrieri said, a property listed at a deeply reduced commission is less likely to be shown by a selling agent who has similar properties at higher commissions.

"In my area, the selling agent is usually very aware of the properties that have been listed at a reduced commission," he said. "And it's a good bet that they're probably going to show those properties last."

Brokers who offer reduced commissions, however, argue that such tools as the Internet allow them to provide competitive levels of service at lower prices.

"The days of the traditional discount broker are over," said Glenn Cohen, founder and president of YHD Realty, formerly Your Home Direct, an Internet-based brokerage in West Long Branch, N.J.

Mr. Cohen said that a customer who lists a property with YHD can choose from several listing plans.

If the seller is willing to show the house himself, YHD charges a commission of just 2 percent.

To earn the commission, Mr. Cohen said, the company advertises the property in print, provides a photographic virtual tour of the property on its Internet site, and pre- screens buyers so that only those who can afford the house will get appointments for a showing by the owner.

Sellers who want to show the house themselves, but who want the listing submitted to the local Multiple Listing Service, he said, are charged a commission of 3.8 percent. Those who want both inclusion in the M.L.S. and a sales agent to show the property pay a commission of 4.3 percent.

With either of these two plans, Mr. Cohen said, YHD guarantees the selling broker a 2.5 percent commission — the same amount the broker would get selling another broker's 5 percent listing.

One type of reduced-commission plan being offered by some brokers is designed to give the listing office the exclusive right to sell a home for a specific period, typically 30 days, after which the home can be sold through other brokers, at a higher commission.

But Jack Hopkins, an associate broker with Century 21 Family Realty in East Northport, N.Y., said that sellers should be cautious about accepting such a deal.

The problem, he said, is that this arrangement often works to the seller's disadvantage.

"The more a property is exposed to potential buyers from day one of the listing, the more likely it is you'll find somebody who wants the home," Mr. Hopkins said. "The problem with 30-day exclusives, though, is that the house is being shown only to the listing agent's buyers for the first 30 days. And 30 days can be a lifetime in the real estate market. One month from now the market will have an entirely different complexion than it does today."

Randi Hutton, a sales agent with Tillman & Frost Coldwell Banker, a brokerage company in Westport, Conn., said that the primary benefit sellers get when they hire a full-service agency — and do not insist on paying a reduced commission — is a full marketing plan for the sale.

"A full-service agent is going to lay out a marketing strategy and an advertising plan," she said. "The agent is going to sit down with you and talk to you about how much your house is worth, she'll show you how to prepare the house for sale, she'll tell you what has to be done and what doesn't have to be done, and she'll figure out the best place to run advertisements that will reach the most likely qualified buyers."

Ms. Hutton said that sellers should interview at least two agents, perhaps more, before signing a listing agreement, particularly one for a drastically reduced commission.

"You want to ask the agent what she's going to do to market your home," she said, adding that sellers should also try to find out how much hand-holding the listing agent will provide once a buyer is found.

"A good agent is going to be totally proactive," Ms. Hutton said. For example, she said, as soon as the listing is taken, an efficient agent will go to the local town hall and obtain copies of everything in the files that pertain to the house.

"I try to put together a file that has paperwork on underground oil tanks, septic systems, well inspections, old building permits, and any other information that can be used to make the deal move smoothly," she said.

The listing agent should also be prepared to cooperate with the selling agent, if the sale is co-brokered, and the buyer's and seller's lawyers to coordinate and schedule the necessary inspections of the house and to assist in getting reports and other documents where they need to go.

"An agent who stands out is one who is on top of her game and thinking ahead," Ms. Hutton said.