Accused killer Dean Faiello is reportedly burning through cash, buying meals and paying off fellow inmates in a Costa Rican jail.  [Foto:  N.Y. Post: Bolivar Arellano]

Faiello, the phony doc charged with the murder of New York investment banker Maria Cruz, has blown through as much as $7,000 in "perks" during his stay in a jail outside San Jose since his Feb. 26 arrest.

Faiello — who fled to Costa Rica before Cruz's body was found buried in a concrete coffin under his former Newark, N.J., home last winter — is fighting extradition on the charges filed by the Manhattan district attorney's office.

Some of the dough Faiello has spent in the slammer has gone toward takeout meals — from McDonald's, Burger King and Pizza Hut — which the quack apparently favors over prison fare of rice and beans.

But Faiello also pays other inmates, presumably to watch his back, sources said.

A longtime drug user — cocaine and the nasal opiate Stahdol are his drugs of choice — Faiello has previously told The Post and close friends that he has AIDS.

"He has complained that he has AIDS, that he isn't getting the drugs he needs and he has to pay for protection," said a Costa Rican source. "You decide what that means."

Meanwhile, Faiello has fired his lawyer, Moises Vincenzi — arguably the best defense attorney in Costa Rica.

"He wanted to be out of jail [immediately], and I couldn't do that right away. He believed I was making a bad defense," said Vincenzi, confirming he'd been axed.

He declined to elaborate, citing the ongoing case.

Asked about Faiello's reported payouts to fellow inmates, Vincenzi, who oversaw Faiello's outside bank account, said his former client had asked him to put money into inmates' jailhouse accounts.

Vincenzi said he refused to do so.

"It was my job to protect him legally, not in jail," Vincenzi said. "It is not my business what he does in jail. I did not get into those issues with him."

Faiello's firing of Vincenzi, said one Costa Rican lawyer, "is definitely a stalling tactic" to delay extradition. It will take time for any new defender to brush up on the case, and delays are "inevitable."

"Dean Faiello thinks he can buy liberty," said another source familiar with the case.

"But Vincenzi doesn't operate that way. He believes in the justice process. If Faiello had had a 'bad defense,' he'd be back in the United States already."

Legal experts in Costa Rica believe extradition for Cruz's murder is likely if — as stipulated in the U.S. extradition treaty — Faiello won't face the death penalty or life in prison.

Faiello recently filed paperwork for a public defender; he has also been in touch with a private lawyer, according to sources.

In July, he appeared twice before Costa Rican judges. The court is still studying the charges and will not allow Faiello out on bail because of the murder charges.

Faiello also faces several counts related to his October 2002 arrest for practicing medicine without a license, and for participating with legit docs in an illegal Stahdol prescription-writing ring.

Cruz went missing in April 2003 after a laser-surgery appointment with Faiello, who had continued to practice despite the October charges against him.

By the time cops discovered the body stuffed in a suitcase under concrete at Faiello's house, he was on the lam.

Margaret Shalley, the New York attorney who has represented Faiello when he was arrested for practicing without a license, said last week she hasn't spoken to him "in months."