Raul, an illegal immigrant from El Salvador, signed a contract last month to pay a District lawyer $2,500 to help him apply for amnesty under the new immigration law.

At the time, Raul, a construction worker who does not want his full name used, did not know that a private, nonprofit legal aid clinic in Adams-Morgan could help him file his amnesty petition for $50.

The wide disparity in the costs of applying for amnesty highlights one of the unintended results of the new immigration law: Lawyers are the prime financial beneficiaries of the amnesty program, and some other entrepreneurs also are trying to get in on the act.

"The big joke is that this is the immigration lawyers relief act of 1986," said immigration lawyer Michael Maggio, who estimated that the practice of many immigration lawyers has doubled because of the amnesty program.

"Lawyers are the great beneficiaries of this regulatory scheme that makes it so difficult for aliens to qualify for legalization," said Maggio, a well-known Washington immigration specialist who charges between $700 and $2,500.

As the one-year amnesty program picks up steam, so has a simmering debate been immigrant ad- vocacy groups and lawyers over the fairness of legal fees.

The advocacy groups claim that some lawyers are unfairly charging immigrants hundreds and sometimes thousands of dollars to process their amnesty claims. But immigration lawyers contend that their fees are justified because the often-complicated cases require substantial time and effort.

Several hundred voluntary agencies have been authorized by the Immigration and Naturalization Service to process amnesty applications, but these agencies cannot charge more than $100 a person.

A telephone survey by The Washington Post of six private lawyers who advertise legal services in local Hispanic publications showed that they are charging immigrants $750 to $2,500 per person to help them process amnesty claims.

The amount depends on the complexity of the case, lawyers say. Higher fees are charged, for example, if the immigrant had been charged with a crime or had entered this country with a visa but remained here illegally after it expired.

"I think some private attorneys are ripping people off," said Yvonne Vega, director of Ayuda, a private, nonprofit legal aid center that charges $50 and is processing 450 amnesty cases. Ayuda officials said they are now handling the case of Raul and are attempting to extricate him from his contract with a private lawyer.

Immigration lawyers say they take on many complicated cases and give immigrants quick and personalized service that volunteer agencies might not provide. Lawyers said their work often requires talking with previous employers and seeking hard-to-get documentation to prove that an applicant has been in this country since the Jan. 1, 1982, amnesty cutoff date.

"I've talked to aliens who said, 'This means an awful lot to me, and I don't want to take any chances, so I'll pay more and go to a lawyer,' " said Jim Tom Haynes, acting coordinator for the legalization assistance project of the American Immigration Lawyers Association.

Maggio agreed: "I'm not saying you can't be served properly {by a voluntary agency}, but there are a large number of people who want the security of professionals."

While many illegal aliens are too poor to afford private lawyers, many middle-class immigrants prefer hiring lawyers because they often provide more individualized attention and speedier processing of their applications.

The amnesty program is drumming up business for nonlawyers as well. American Amnesty Immigration Service, a District-based company, is selling $5,000 kits to teach lawyers and other professionals how to set up amnesty businesses.

A brochure that the company sends to prospective buyers boasts: "Now, you can take advantage of a golden opportunity . . . . The nation's fastest growing market is now ready to be tapped . . . . An estimated 8.7 million immigrants need your help . . . . "

A letter that is signed by the firm's national sales director, Martin L. Rubin, and that accompanies the brochure recommends that amnesty seekers be charged $400 to $1,500.

Two company employes said Rubin is in California until later this month and cannot be reached to answer questions about his business.

Immigration Service spokesman Duke Austin said officials know about American Amnesty Immigration Service from other media inquiries. The company applied for the immigration agency's permission to act as a voluntary agency to process amnesty claims but was denied because its application was late, Austin said.

Austin said the new immigration law was intended so that people can apply for amnesty on their own, but many people are hampered by language problems.

"Routinely, it's not necessary" for amnesty applicants to use lawyers, Austin said, although sometimes a lawyer can provide valuable assistance such as getting an employment letter from a reticent employer.

Not all lawyers are benefiting financially from the amnesty program.

Some are giving immigrants free legal advice through the alien rights law project of the Washington Lawyers Committee for Civil Rights. The committee has been conducting amnesty training seminars.

After the training, the lawyers agree to offer free legal advice to the voluntary agencies as they process the amnesty claims. Some lawyers are available for phone consultations on the most difficult cases. Other lawyers work at the voluntary agencies.

Six prestigious Washington-based law firms have "adopted" some of the voluntary agencies and are giving them free legal advice, said Debbie Standiford, legalization coordinator for the Washington Lawyers Committee for Civil Rights.

Many illegal immigrants have no choice but to go through a voluntary agency.

Jose and Gilda, a Guatemalan couple living in Silver Spring, first approached a lawyer in the District about filing an amnesty claim for them and three of their four children. The lawyer wanted $3,000.

The couple, who did not want their last names used, did not have the money, so they processed their papers through a voluntary agency in Takoma Park. The agency charged them $325. "If we had had the money, we would have paid the lawyer," said Jose, 42, who cleans offices.

And Raul is trying to back out of his agreement to pay a lawyer $2,500 for his amnesty application so that Ayuda can do the same work for $50.

The 30-year-old construction worker has paid the lawyer a $150 deposit, and $150 is due this week.

Ayuda social worker Shelly Jones helped Raul write a letter explaining that he cannot afford the $2,500 fee. Raul plans to take the letter to the lawyer's office this week. "I told {Raul} that the lawyer will probably {process his application} faster than we could because we have 450 cases," Jones said. "But we will get it done."