Claus von Bu low was sentenced three years ago to 30 years in prison. He woke in his rooms at 960 Fifth Ave. yesterday morning a "relieved" man, a free man, and, by a jury's ruling, an innocent man. But is he a rich man?

How will he pay for years of legal fees, estimated by some at around $1 million? What pays for the omelets at Mortimer's on Lexington Avenue, the custom-made suits with the razor-cut sleeve cuffs, the fees at the Knickerbocker Club? "Money is the sinews of affairs," an ancient Greek said, and money is certainly the sinews of the von Bu low affair. No lucre, no allure.

Most of von Bu low's wealth is potential wealth. Five years ago his wife's estate, the product of a Pittsburgh utilities fortune, was estimated at $75 million. Her will at the time dictated that on her death von Bu low would receive $14 million, the Fifth Avenue apartment and Clarendon Court, an ocean-front mansion in Newport. The estate of Martha (Sunny) von Bu low has grown since, some say, by as much as twofold. Had von Bu low been convicted again, he would not have received a dime.

Von Bu low now lives off part of the income from a $2 million trust fund his wife established for him before lapsing into her second coma in December, 1980. The income from the trust is estimated at $120,000 a year; in 1982 he told The Washington Post that his total income that year was $280,000, making him comfortable by any standard, but not wildly rich. He will, no doubt, earn handsome sums for his memoirs and film rights to his story, both of which have been sold.

Von Bu low told reporters in the weeks during this last trial on charges of twice attempting to murder his wife that he also has other sources of income. He would not say what they are. Sunny von Bu low's trust officers take care of expenses on the apartment in New York and the Newport estate.

Von Bu low said after the trial that he would not marry his latest companion, Andrea Reynolds, nor does he plan to divorce his wife, who lies in a permanent coma in a hospital room in New York. He told The Providence Journal a divorce would "be in bad taste."

In an interview after the verdict with WJAR-TV in Providence, von Bu low said, "Sunny is somebody I love, whom I still love the memory of. This whole story is a tragedy. Because Sunny and I had difficulties in our marriage does not mean there was not emotion between us." WJAR's interview, broadcast only in the Providence area, scooped Barbara Walters' "exclusive" postverdict interview scheduled for tomorrow night's broadcast of the ABC magazine show "20/20."

After the verdict was announced Monday morning, von Bu low said he would take a vacation with Reynolds "in a little hidden place where no one will know us." Then, he said, he has "excellent prospects" for employment.

Born to a considerably more modest fortune 58 years ago in Copenhagen, von Bu low earned a law degree from Cambridge University, then worked briefly in London as a young man at Hambro's Bank; at London's central criminal court, the Old Bailey; and in the chambers of one Lord Hailsham. Von Bu low met oil magnate J. Paul Getty at a party in 1959 and worked as his aide until 1968. Except for devising tax shelters in his wife's will, von Bu low has not worked since.

Now that he has been exonerated of criminal charges, von Bu low will be entitled to his inheritance when his wife dies. Doctors say that could be 20 years or more. Alexander von Auersperg and Annie-Laurie Kneissl, von Bu low's principal accusers, said they were not sure if they would pursue civil suits to change their mother's will.

Houses, money, apartments are not the principal issue, Kneissl said. "We're well provided for."

To say the least. When Sunny von Bu low's mother Annie-Laurie Aitken died, she left a fortune estimated at nearly $100 million, mainly to Kneissl and von Auersperg. Aitken disinherited her other grandchild, Cosima von Bu low, for siding with her father in the attempted-murder case.

Kneissl and von Auersperg said they still believe their stepfather tried to kill their mother, but they said they would like to meet with their stepsister, something they have not done since Von Bulow's first trial.

"I would hope that [Cosima] still loves us," Kneissl said. "We certainly love her. I feel that she took the side that she had to take. We understand that very well. She's lost a mother. It must have been very difficult to be on the verge of losing a father."

Some of the spectators who followed the von Bu low affair when it first came to trial three years ago in Newport said the second trial was relatively dull, dominated as it was by mountains of medical testimony. What was missing, they said, was the money.

Judge Corinne P. Grande did not allow the prosecution to present testimony from Sunny von Bu low's financial consultant, G. Morris Gurley of New York's Chemical Bank. Kneissl and von Auersperg and the prosecutors said the judge's decision to disallow such testimony led to Claus von Bu low's acquittal. Without knowing in detail about the money, they said, no juror could understand the full force of the possible motive.

Claus von Bu low still keeps framed photographs of his wife in his study, his bedroom, his library. "You think of the happy moments," he said.